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26 Jan 2022 at 01:30
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Bibliography on: Pangenome


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RJR: Recommended Bibliography 26 Jan 2022 at 01:30 Created: 


Although the enforced stability of genomic content is ubiquitous among MCEs, the opposite is proving to be the case among prokaryotes, which exhibit remarkable and adaptive plasticity of genomic content. Early bacterial whole-genome sequencing efforts discovered that whenever a particular "species" was re-sequenced, new genes were found that had not been detected earlier — entirely new genes, not merely new alleles. This led to the concepts of the bacterial core-genome, the set of genes found in all members of a particular "species", and the flex-genome, the set of genes found in some, but not all members of the "species". Together these make up the species' pan-genome.

Created with PubMed® Query: pangenome or "pan-genome" or "pan genome" NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)


RevDate: 2022-01-18

Moller AG, Petit RA, TD Read (2022)

Species-Scale Genomic Analysis of Staphylococcus aureus Genes Influencing Phage Host Range and Their Relationships to Virulence and Antibiotic Resistance Genes.

mSystems [Epub ahead of print].

Phage therapy has been proposed as a possible alternative treatment for infections caused by the ubiquitous bacterial pathogen Staphylococcus aureus. However, successful therapy requires understanding the genetic basis of host range-the subset of strains in a species that could be killed by a particular phage. We searched diverse sets of S. aureus public genome sequences against a database of genes suggested from prior studies to influence host range to look for patterns of variation across the species. We found that genes encoding biosynthesis of molecules that were targets of S. aureus phage adsorption to the outer surface of the cell were the most conserved in the pangenome. Putative phage resistance genes that were core components of the pangenome genes had similar nucleotide diversity, ratio of nonsynonymous to synonymous substitutions, and functionality (measured by delta-bitscore) to other core genes. However, phage resistance genes that were not part of the core genome were significantly less consistent with the core genome phylogeny than all noncore genes in this set, suggesting more frequent movement between strains by horizontal gene transfer. Only superinfection immunity genes encoded by temperate phages inserted in the genome correlated with experimentally determined temperate phage resistance. Taken together, these results suggested that, while phage adsorption genes are heavily conserved in the S. aureus species, HGT may play a significant role in strain-specific evolution of host range patterns. IMPORTANCE Staphylococcus aureus is a widespread, hospital- and community-acquired pathogen that is commonly antibiotic resistant. It causes diverse diseases affecting both the skin and internal organs. Its ubiquity, antibiotic resistance, and disease burden make new therapies urgent, such as phage therapy, in which viruses specific to infecting bacteria clear infection. S. aureus phage host range not only determines whether phage therapy will be successful by killing bacteria but also horizontal gene transfer through transduction of host genetic material by phages. In this work, we comprehensively reviewed existing literature to build a list of S. aureus phage resistance genes and searched our database of almost 43,000 S. aureus genomes for these genes to understand their patterns of evolution, finding that prophages' superinfection immunity correlates best with phage resistance and HGT. These findings improved our understanding of the relationship between known phage resistance genes and phage host range in the species.

RevDate: 2022-01-18

Alvarez-Fraga L, Phan MD, Goh KGK, et al (2022)

Differential Afa/Dr Fimbriae Expression in the Multidrug-Resistant Escherichia coli ST131 Clone.

mBio [Epub ahead of print].

Many antibiotic resistant uropathogenic Escherichia coli (UPEC) strains belong to clones defined by their multilocus sequence type (ST), with ST131 being the most dominant. Although we have a good understanding of resistance development to fluoroquinolones and third-generation cephalosporins by ST131, our understanding of the virulence repertoire that has contributed to its global dissemination is limited. Here we show that the genes encoding Afa/Dr fimbriae, a group of adhesins strongly associated with UPEC that cause gestational pyelonephritis and recurrent cystitis, are found in approximately one third of all ST131 strains. Sequence comparison of the AfaE adhesin protein revealed a unique allelic variant carried by 82.9% of afa-positive ST131 strains. We identify the afa regulatory region as a hotspot for the integration of insertion sequence (IS) elements, all but one of which alter afa transcription. Close investigation demonstrated that the integration of an IS1 element in the afa regulatory region leads to increased expression of Afa/Dr fimbriae, promoting enhanced adhesion to kidney epithelial cells and suggesting a mechanism for altered virulence. Finally, we provide evidence for a more widespread impact of IS1 on ST131 genome evolution, suggesting that IS dynamics contribute to strain level microevolution that impacts ST131 fitness. IMPORTANCE E. coli ST131 is the most common antibiotic resistant UPEC clone associated with human urinary tract and bloodstream infections. Understanding the features of ST131 that have driven its global dissemination remains a critical priority if we are to counter its increasing antibiotic resistance. Here, we utilized a large collection of ST131 isolates to investigate the prevalence, regulation, and function of Afa/Dr fimbriae, a well-characterized UPEC colonization and virulence factor. We show that the afa genes are found frequently in ST131 and demonstrate how the integration of IS elements in the afa regulatory region modulates Afa expression, presenting an example of altered virulence capacity. We also exploit a curated set of ST131 genomes to map the integration of the antibiotic resistance-associated IS1 element in the ST131 pangenome, providing evidence for its widespread impact on ST131 genome evolution.

RevDate: 2022-01-17

Ruperao P, Gandham P, A Rathore (2022)

Construction of Practical Haplotype Graph (PHG) with the Whole-Genome Sequence Data.

Methods in molecular biology (Clifton, N.J.), 2443:273-284.

With the emerging sequencing technologies and cost reduction, the sequence data generation has accelerated from a single individual to multiple (thousands of) individuals of a species. The terabytes of sequence data generated from thousands of individuals include the majority of the redundant sequence which depends on the level of sequence similarity within the population of individuals. Managing large datasets and creating the unique catalogue sequence from such a large population is challenging to analyze, store, and retrieve the information. In this chapter, we discuss the practical haplotype graph (PHG) which addresses the above said challenges and also able to retrieve required information such as variants and sequences more efficiently, which enable researchers to manage and assess large genomic data.

RevDate: 2022-01-17

Tay Fernandez C (2022)

Making a Pangenome Using the Iterative Mapping Approach.

Methods in molecular biology (Clifton, N.J.), 2443:259-271.

Pangenomes have replaced single reference genomes as genetic references, as they contain a better scope of the diversity found in a single species. This protocol outlines the iterative mapping approach in constructing a pangenome, including how to check the raw data, align the data to a reference, how to assemble the data, and how to remove potential contaminants from the final assembly.

RevDate: 2022-01-17

Kamal N, Lux T, Jayakodi M, et al (2022)

The Barley and Wheat Pan-Genomes.

Methods in molecular biology (Clifton, N.J.), 2443:147-159.

To unlock the genetic potential in crops, multi-genome comparisons are an essential tool. Decreasing costs and improved sequencing technologies have democratized plant genome sequencing and led to a vast increase in the amount of available reference sequences on the one hand and enabled the assembly of even the largest and most complex and repetitive crops genomes such as wheat and barley. These developments have led to the era of pan-genomics in recent years. Pan-genome projects enable the definition of the core and dispensable genome for various crop species as well as the analysis of structural and functional variation and hence offer unprecedented opportunities for exploring and utilizing the genetic basis of natural variation in crops. Comparing, analyzing, and visualizing these multiple reference genomes and their diversity requires powerful and specialized computational strategies and tools.

RevDate: 2022-01-17

Tello-Ruiz MK, Jaiswal P, D Ware (2022)

Gramene: A Resource for Comparative Analysis of Plants Genomes and Pathways.

Methods in molecular biology (Clifton, N.J.), 2443:101-131.

Gramene is an integrated bioinformatics resource for accessing, visualizing, and comparing plant genomes and biological pathways. Originally targeting grasses, Gramene has grown to host annotations for over 90 plant genomes including agronomically important cereals (e.g., maize, sorghum, wheat, teff), fruits and vegetables (e.g., apple, watermelon, clementine, tomato, cassava), specialty crops (e.g., coffee, olive tree, pistachio, almond), and plants of special or emerging interest (e.g., cotton, tobacco, cannabis, or hemp). For some species, the resource includes multiple varieties of the same species, which has paved the road for the creation of species-specific pan-genome browsers. The resource also features plant research models, including Arabidopsis and C4 warm-season grasses and brassicas, as well as other species that fill phylogenetic gaps for plant evolution studies. Its strength derives from the application of a phylogenetic framework for genome comparison and the use of ontologies to integrate structural and functional annotation data. This chapter outlines system requirements for end-users and database hosting, data types and basic navigation within Gramene, and provides examples of how to (1) explore Gramene's search results, (2) explore gene-centric comparative genomics data visualizations in Gramene, and (3) explore genetic variation associated with a gene locus. This is the first publication describing in detail Gramene's integrated search interface-intended to provide a simplified entry portal for the resource's main data categories (genomic location, phylogeny, gene expression, pathways, and external references) to the most complete and up-to-date set of plant genome and pathway annotations.

RevDate: 2022-01-17

Redsun S, Hokin S, Cameron CT, et al (2022)

Doing Genetic and Genomic Biology Using the Legume Information System and Associated Resources.

Methods in molecular biology (Clifton, N.J.), 2443:81-100.

In this chapter, we introduce the main components of the Legume Information System (https://legumeinfo.org) and several associated resources. Additionally, we provide an example of their use by exploring a biological question: is there a common molecular basis, across legume species, that underlies the photoperiod-mediated transition from vegetative to reproductive development, that is, days to flowering? The Legume Information System (LIS) holds genetic and genomic data for a large number of crop and model legumes and provides a set of online bioinformatic tools designed to help biologists address questions and tasks related to legume biology. Such tasks include identifying the molecular basis of agronomic traits; identifying orthologs/syntelogs for known genes; determining gene expression patterns; accessing genomic datasets; identifying markers for breeding work; and identifying genetic similarities and differences among selected accessions. LIS integrates with other legume-focused informatics resources such as SoyBase (https://soybase.org), PeanutBase (https://peanutbase.org), and projects of the Legume Federation (https://legumefederation.org).

RevDate: 2022-01-18

Sutton G, Fogel GB, Abramson B, et al (2021)

Horizontal transfer and evolution of wall teichoic acid gene cassettes in Bacillus subtilis.

F1000Research, 10:354.

Background: Wall teichoic acid (WTA) genes are essential for production of cell walls in gram-positive bacteria and necessary for survival and variability in the cassette has led to recent antibiotic resistance acquisition in pathogenic bacteria. Methods: Using a pan-genome approach, we examined the evolutionary history of WTA genes in Bacillus subtilis ssp. subtilis. Results: Our analysis reveals an interesting pattern of evolution from the type-strain WTA gene cassette possibly resulting from horizontal acquisition from organisms with similar gene sequences. The WTA cassettes have a high level of variation which may be due to one or more independent horizontal transfer events during the evolution of Bacillus subtilis ssp. subtilis. This swapping of entire WTA cassettes and smaller regions within the WTA cassettes is an unusual feature in the evolution of the Bacillus subtilis genome and highlights the importance of horizontal transfer of gene cassettes through homologous recombination within B. subtilis or other bacterial species. Conclusions: Reduced sequence conservation of these WTA cassettes may indicate a modified function like the previously documented WTA ribitol/glycerol variation. An improved understanding of high-frequency recombination of gene cassettes has ramifications for synthetic biology and the use of B. subtilis in industry.

RevDate: 2022-01-13

Hoopes G, Meng X, Hamilton JP, et al (2022)

Phased, chromosome-scale genome assemblies of tetraploid potato reveals a complex genome, transcriptome, and predicted proteome landscape underpinning genetic diversity.

Molecular plant pii:S1674-2052(22)00003-X [Epub ahead of print].

Cultivated potato is a clonally propagated autotetraploid species with a highly heterogeneous genome. Phased assemblies of six cultivars including two chromosome-scale phased genome assemblies revealed extensive allelic diversity including altered coding and transcript sequences, preferential allele expression, and structural variation that collectively result in a highly complex transcriptome and predicted proteome which are distributed across the homologous chromosomes. Wild species contribute to the extensive allelic diversity in tetraploid cultivars, demonstrating ancestral introgressions predating modern breeding efforts. As a clonally propagated autotetraploid that undergoes limited meiosis, dysfunctional and deleterious alleles are not purged in tetraploid potato. Nearly a quarter of the loci bore mutations predicted to have a high negative impact on protein function, complicating breeder's efforts to reduce genetic load. The StCDF1 locus controls maturity and analysis of six tetraploid genomes revealed 12 allelic variants correlated with maturity in a dosage dependent manner. Knowledge of the complexity of the tetraploid potato genome with its rampant structural variation and embedded deleterious and dysfunctional alleles will be key not only to implementing precision breeding of tetraploid cultivars but also to the construction of homozygous, diploid potato germplasm containing favorable alleles to capitalize on heterosis in F1 hybrids.

RevDate: 2022-01-13

Sakkour A, Mascher M, Himmelbach A, et al (2022)

Chromosome-scale assembly of barley Cv. 'Haruna Nijo' as a resource for barley genetics.

DNA research : an international journal for rapid publication of reports on genes and genomes pii:6505204 [Epub ahead of print].

Cultivated barley (Hordeum vulgare ssp. vulgare) is used for food, animal feed, and alcoholic beverages and is widely grown in temperate regions. Both barley and its wild progenitor (H. vulgare ssp. spontaneum) have large 5.1-Gb genomes. High-quality chromosome-scale assemblies for several representative barley genotypes, both wild and domesticated, have been constructed recently to populate the nascent barley pan-genome infrastructure. Here, we release a chromosome-scale assembly of the Japanese elite malting barley cultivar 'Haruna Nijo' using a similar methodology as in the barley pan-genome project. The 4.28-Gb assembly had a scaffold N50 size of 18.9 Mb. The assembly showed high collinearity with the barley reference genome 'Morex' cultivar, with some inversions. The pseudomolecule assembly was characterized using transcript evidence of gene projection derived from the reference genome and de novo gene annotation achieved using published full-length cDNA sequences and RNA-Seq data for 'Haruna Nijo'. We found good concordance between our whole-genome assembly and the publicly available BAC clone sequence of 'Haruna Nijo'. Interesting phenotypes have since been identified in Haruna Nijo; its genome sequence assembly will facilitate the identification of the underlying genes.

RevDate: 2022-01-12

Maqbool S, Hassan MA, Xia X, et al (2022)

Root system architecture in cereals: progress, challenges, and perspective.

The Plant journal : for cell and molecular biology [Epub ahead of print].

Roots are essential multifunctional plant organs involved in water and nutrient uptake, metabolite storage, anchorage, mechanical support, and interaction with the soil environment. Understanding of this 'hidden half' will provide potential for manipulation of root system architecture (RSA) traits to optimize resource use efficiency and grain yield in cereal crops. Unfortunately, root traits are highly neglected in breeding due to the challenges of phenotyping but could have large rewards if the variability in RSA traits can be fully exploited. Until now, a plethora of genes have been characterized in detail for their potential role in improving RSA. The use of forward genetics approaches to find sequence variations in genes underpinning desirable RSA would be highly beneficial. Advances in computer vision applications have allowed image-based approaches for high-throughput phenotyping of RSA traits that can be used by any laboratory worldwide to make progress in understanding root function and dissection of the genetics. At the same time, the frontiers of root measurement include non-invasive methods like X-ray CT and MRI that will allow new types of temporal studies. Root physiology and ecology is further supported by spatiotemporal root simulation modelling. The discovery of component traits providing improved resilience and yield advantage in target environments is a key necessity for mainstreaming root-based cereal breeding. The integrated use of pan-genome resources, now available in most cereals, coupled with new in-field phenotyping platforms has the potential for precise selection of superior genotypes with improved RSA.

RevDate: 2022-01-11

Gladman N, Olson A, Wei S, et al (2022)

SorghumBase: a web-based portal for sorghum genetic information and community advancement.

Planta, 255(2):35.

MAIN CONCLUSION: SorghumBase provides a community portal that integrates genetic, genomic, and breeding resources for sorghum germplasm improvement. Public research and development in agriculture rely on proper data and resource sharing within stakeholder communities. For plant breeders, agronomists, molecular biologists, geneticists, and bioinformaticians, centralizing desirable data into a user-friendly hub for crop systems is essential for successful collaborations and breakthroughs in germplasm development. Here, we present the SorghumBase web portal (https://www.sorghumbase.org), a resource for the sorghum research community. SorghumBase hosts a wide range of sorghum genomic information in a modular framework, built with open-source software, to provide a sustainable platform. This initial release of SorghumBase includes: (1) five sorghum reference genome assemblies in a pan-genome browser; (2) genetic variant information for natural diversity panels and ethyl methanesulfonate (EMS)-induced mutant populations; (3) search interface and integrated views of various data types; (4) links supporting interconnectivity with other repositories including genebank, QTL, and gene expression databases; and (5) a content management system to support access to community news and training materials. SorghumBase offers sorghum investigators improved data collation and access that will facilitate the growth of a robust research community to support genomics-assisted breeding.

RevDate: 2022-01-10

MacKenzie K, Marshall J, Wright F, et al (2022)

Phylogeny and potential virulence of cryptic clade Escherichia coli species complex isolates derived from an arable field trial.

Current research in microbial sciences, 3:100093 pii:S2666-5174(21)00073-0.

Analysis of Escherichia coli taxonomy has expanded into a species-complex with the identification of divergent cryptic clades. A key question is the evolutionary trajectory of these clades and their relationship to isolates of clinical or veterinary importance. Since they have some environmental association, we screened a collection of E. coli isolated from a long-term spring barley field trial for their presence. While most isolates clustered into the enteric-clade, four of them clustered into Clade-V, and one in Clade-IV. The Clade -V isolates shared >96% intra-clade average nucleotide sequence identity but <91% with other clades. Although pan-genomics analysis confirmed their taxonomy as Clade -V (E. marmotae), retrospective phylogroup PCR did not discriminate them correctly. Differences in metabolic and adherence gene alleles occurred in the Clade -V isolates compared to E. coli sensu scricto. They also encoded the bacteriophage phage-associated cyto-lethal distending toxin (CDT) and antimicrobial resistance (AMR) genes, including an ESBL, blaOXA-453. Thus, the isolate collection encompassed a genetic diversity, and included cryptic clade isolates that encode potential virulence factors. The analysis has determined the phylogenetic relationship of cryptic clade isolates with E. coli sensu scricto and indicates a potential for horizontal transfer of virulence factors.

RevDate: 2022-01-08

Neupane S, Bonilla SI, Manalo AM, et al (2022)

Complete de novo assembly of Wolbachia endosymbiont of Diaphorina citri Kuwayama (Hemiptera: Liviidae) using long-read genome sequencing.

Scientific reports, 12(1):125.

Wolbachia, a gram-negative [Formula: see text]-proteobacterium, is an endosymbiont found in some arthropods and nematodes. Diaphorina citri Kuwayama, the vector of 'Candidatus Liberibacter asiaticus' (CLas), are naturally infected with a strain of Wolbachia (wDi), which has been shown to colocalize with the bacteria pathogens CLas, the pathogen associated with huanglongbing (HLB) disease of citrus. The relationship between wDi and CLas is poorly understood in part because the complete genome of wDi has not been available. Using high-quality long-read PacBio circular consensus sequences, we present the largest complete circular wDi genome among supergroup-B members. The assembled circular chromosome is 1.52 megabases with 95.7% genome completeness with contamination of 1.45%, as assessed by checkM. We identified Insertion Sequences (ISs) and prophage genes scattered throughout the genomes. The proteins were annotated using Pfam, eggNOG, and COG that assigned unique domains and functions. The wDi genome was compared with previously sequenced Wolbachia genomes using pangenome and phylogenetic analyses. The availability of a complete circular chromosome of wDi will facilitate understanding of its role within the insect vector, which may assist in developing tools for disease management. This information also provides a baseline for understanding phylogenetic relationships among Wolbachia of other insect vectors.

RevDate: 2022-01-08

Liang Y, Huang Y, Chen K, et al (2022)

Characterization of non-specific lipid transfer protein (nsLtp) gene families in the Brassica napus pangenome reveals abundance variation.

BMC plant biology, 22(1):21.

BACKGROUND: Brassica napus is an important agricultural species, improving stress resistance was one of the main breeding goals at present. Non-specific lipid transfer proteins (nsLTPs) are small, basic proteins which are involved in some biotic or abiotic stress responses. B. napus is susceptible to a variety of fungal diseases, so identify the BnLTPs and their expression in disease responses is very important. The common reference genome of B. napus does not contain all B. napus genes because of gene presence/absence variations between individuals. Therefore, it was necessary to search for candidate BnLTP genes in the B. napus pangenome.

RESULTS: In the present study, the BnLTP genes were identified throughout the pangenome, and different BnLTP genes were presented among varieties. Totally, 246 BnLTP genes were identified and could be divided into five types (1, 2, C, D, and G). The classification, phylogenetic reconstruction, chromosome distribution, functional annotation, and gene expression were analyzed. We also identified potential cis-elements that respond to biotic and abiotic stresses in the 2 kb upstream regions of all BnLTP genes. RNA sequencing analysis showed that the BnLTP genes were involved in the response to Sclerotinia sclerotiorum infection. We identified 32 BnLTPs linked to blackleg resistance quantitative trait locus (QTL).

CONCLUSION: The identification and analysis of LTP genes in the B. napus pangenome could help to elucidate the function of BnLTP family members and provide new information for future molecular breeding in B. napus.

RevDate: 2022-01-05

Yang SM, Kim E, Lee W, et al (2022)

Genomic characteristics and comparative genomics of Salmonella enterica subsp. enterica serovar Schwarzengrund strain S16 isolated from chicken feces.

Gut pathogens, 14(1):1.

BACKGROUND: Salmonella enterica subsp. enterica serovar Schwarzengrund (S. Schwarzengrund) is most frequently isolated from commensals humans or poultry. Here we report S. Schwarzengrund strain S16, the first sequenced genome in the Republic of Korea. Additionally, genome sequencing for strain S16 was performed and compared with other S. Schwarzengrund genomes obtained from public database.

RESULTS: Strain S16 was isolated from chicken feces. The complete genome consists of one chromosome and one plasmid. The genome size is 4,822,755 bp with 4852 coding sequences. Strain S16 was determined as serovar Schwarzengrund by in silico serotyping and typed as sequence type (ST) 96. Forty-six S. Schwarzengrund genomes yielded a pangenome of 7112 genes, core-genome of 3374 genes, accessory-genome of 2906 genes, and unique-genome of 835 genes. Eighty-one genes were unique to strain S16, including hypothetical proteins and transcriptional regulators. Genotypic analysis of antibiotic resistance of strain S16 confirmed resistance to amikacin, ciprofloxacin, sulfamethoxazole, streptomycin, and tetracycline. Unlike other S. Schwarzengrund genomes, strain S16 had a mutation of gyrB. Moreover, similar to other S. Schwarzengrund genomes reported in other countries, strain S16 was harbored for 153 virulence genes including Saf operon and cdtB gene. All the antibiotic resistance genes and virulence genes were present in the core- or accessory-genomes.

CONCLUSIONS: Complete genome of strain S16 was sequenced. Comparative genomic analysis revealed several genes responsible for antibiotic resistance and specific genomic features of strain S16 and identified virulence factors that might contribute to the human and animal pathogenicity of other S. Schwarzengrund genomes.

RevDate: 2022-01-05

Hyun JC, Monk JM, BO Palsson (2022)

Comparative pangenomics: analysis of 12 microbial pathogen pangenomes reveals conserved global structures of genetic and functional diversity.

BMC genomics, 23(1):7.

BACKGROUND: With the exponential growth of publicly available genome sequences, pangenome analyses have provided increasingly complete pictures of genetic diversity for many microbial species. However, relatively few studies have scaled beyond single pangenomes to compare global genetic diversity both within and across different species. We present here several methods for "comparative pangenomics" that can be used to contextualize multi-pangenome scale genetic diversity with gene function for multiple species at multiple resolutions: pangenome shape, genes, sequence variants, and positions within variants.

RESULTS: Applied to 12,676 genomes across 12 microbial pathogenic species, we observed several shared resolution-specific patterns of genetic diversity: First, pangenome openness is associated with species' phylogenetic placement. Second, relationships between gene function and frequency are conserved across species, with core genomes enriched for metabolic and ribosomal genes and accessory genomes for trafficking, secretion, and defense-associated genes. Third, genes in core genomes with the highest sequence diversity are functionally diverse. Finally, certain protein domains are consistently mutation enriched across multiple species, especially among aminoacyl-tRNA synthetases where the extent of a domain's mutation enrichment is strongly function-dependent.

CONCLUSIONS: These results illustrate the value of each resolution at uncovering distinct aspects in the relationship between genetic and functional diversity across multiple species. With the continued growth of the number of sequenced genomes, these methods will reveal additional universal patterns of genetic diversity at the pangenome scale.

RevDate: 2022-01-04

Li L, Zhou J, Li M, et al (2022)

Comparative Genomic Analysis of Streptococcus pneumoniae Strains: Penicillin Non-susceptible Multi-drug-Resistant Serotype 19A Isolates.

Current microbiology, 79(2):49.

Streptococcus pneumoniae can cause several diseases including otitis media, sinusitis, pneumonia, sepsis and meningitis. The introduction of pneumococcal vaccines has changed the molecular epidemiological and antibiotic resistance profiles of related diseases. Analysis of molecular patterns and genome sequences of clinical strains may facilitate the identification of novel drug resistance mechanism. Three multidrug resistance 19A isolates were verified, serotyped and the complete genomes were sequenced combining the Pacific Biosciences and the Illumina Miseq platform. Genomic annotation revealed that similar central networks were found in the clinical isolates, and Mauve alignments indicated high similarity between different strains. The pan-genome analysis showed the shared and unique cluster in the strains. Mobile elements were predicted in the isolates including prophages and CRISPER systems, which may participate in the virulence and antibiotic resistance of the strains. The presence of 31 virulence factor genes was predicted from other pathogens for PRSP 19339 and 19343, while 30 for PRSP 19087. Meanwhile, 33 genes antibiotic resistance genes were predicted including antibiotic resistance genes, antibiotic-target genes and antibiotic biosynthesis genes. Further analysis of the antibiotic resistance genes revealed new mutations in the isolates. By comparative genomic analysis, we contributed to the understanding of resistance mechanism of the clinical isolates with other serotype strains, which could facilitate the concrete drug resistance mechanism study.

RevDate: 2022-01-04

Zhou H, Zhang J, Shao Y, et al (2022)

Development of a high resolution melting method based on a novel molecular target for discrimination between Bacillus cereus and Bacillus thuringiensis.

Food research international (Ottawa, Ont.), 151:110845.

Delimitation within the Bacillus cereus group is confusing due to the highly similar genetic background of its constituent bacteria. This study aimed to develop a rapid and efficient method for the identification of Bacillus cereus and Bacillus thuringiensis, two closely related species within the B. cereus group. Using average nucleotide identity analysis (ANI) and ribosomal multilocus sequence typing (rMLST), the authenticity of the genomes of B. cereus and B. thuringiensis was determined. Emetic B. cereus and Bacillus bombysepticus were also included to provide novel genomic insights into the boundaries within the B. cereus group. Using pan-genome analysis, ispD, a novel core and single-copy molecular target, was identified for the differentiation between B. cereus and B. thuringiensis. Based on the single nucleotide polymorphism within ispD, a high resolution melting (HRM) method for the determination of B. cereus and B. thuringiensis was developed. This method can not only distinguish B. cereus and B. thuringiensis, but can also separate B. cereus from other foodborne pathogenic bacteria. The detection limit of this method could reach 1 pg of pure genomic DNA and 3.7 × 102 cfu/mL of pure culture. Moreover, this new method could effectively differentiate B. cereus and B. thuringiensis in spiked, mixed, and real food samples. Collectively, the established HRM method can provide a new reference paradigm for the sensitive and specific nucleic acid detection of pathogens with identical genomes.

RevDate: 2022-01-04

Khazaei H, O'Sullivan DM, Stoddard FL, et al (2021)

Recent advances in faba bean genetic and genomic tools for crop improvement.

Legume science, 3(3):e75.

Faba bean (Vicia faba L.), a member of the Fabaceae family, is one of the important food legumes cultivated in cool temperate regions. It holds great importance for human consumption and livestock feed because of its high protein content, dietary fibre, and nutritional value. Major faba bean breeding challenges include its mixed breeding system, unknown wild progenitor, and genome size of ~13 Gb, which is the largest among diploid field crops. The key breeding objectives in faba bean include improved resistance to biotic and abiotic stress and enhanced seed quality traits. Regarding quality traits, major progress on reduction of vicine-convicine and seed coat tannins, the main anti-nutritional factors limiting faba bean seed usage, have been recently achieved through gene discovery. Genomic resources are relatively less advanced compared with other grain legume species, but significant improvements are underway due to a recent increase in research activities. A number of bi-parental populations have been constructed and mapped for targeted traits in the last decade. Faba bean now benefits from saturated synteny-based genetic maps, along with next-generation sequencing and high-throughput genotyping technologies that are paving the way for marker-assisted selection. Developing a reference genome, and ultimately a pan-genome, will provide a foundational resource for molecular breeding. In this review, we cover the recent development and deployment of genomic tools for faba bean breeding.

RevDate: 2022-01-03

Basharat Z, Akhtar U, Khan K, et al (2021)

Differential analysis of Orientia tsutsugamushi genomes for therapeutic target identification and possible intervention through natural product inhibitor screening.

Computers in biology and medicine, 141:105165 pii:S0010-4825(21)00959-8 [Epub ahead of print].

Orientia tsutsugamushi (Ott) is a causative agent of scrub typhus, and one of the emerging pathogens that could affect a large human population. It is one of the misdiagnosed and under-reported, febrile illnesses that infects various body organs (skin, heart, lung, kidney, and brain). The control of this infection is hampered due to the lack of drugs or vaccine against it. This study was undertaken to identify potential drug targets from the core genome of Ott and investigate novel natural product inhibitors against them. Hence, the available genomes for 22 strains of Ott were downloaded from the PATRIC database, and pan-genomic analysis was performed. Only 202 genes were present in the core region. Among these, 94 were identified as essential, 32 non-homologous to humans, nine non-homologous to useful gut flora and a single gene dapD as a drug target. Product of this gene (2,3,4,5-tetrahydropyridine-2-carboxylate N-succinyltransferase) was modeled and docked against traditional Indian (Ayurvedic) and Chinese phytochemical libraries, with best hits selected for docking, based on multiple target-drug/s interactions and minimum energy scores. ADMET profiling and molecular dynamics simulation was performed for top three compounds from each library to assess the toxicity and stability, respectively. We presume that these compounds (ZINC8214635, ZINC32793028, ZINC08101133, ZINC85625167, ZINC06018678, and ZINC13377938) could be successful inhibitors of Ott. However, in-depth experimental and clinical research is needed for further validation.

RevDate: 2021-12-28

Xu L, Ying JJ, Fang YC, et al (2021)

Halomonas populi sp. nov. isolated from Populus euphratica.

Archives of microbiology, 204(1):86.

Three yellow-pigmented, Gram-stain-negative, aerobic, motile by flagella and rod-shaped strains, designated as MCT, PC and RC, were isolated from stems of Populus euphratica. Growth of those three strains occurs at 4-40 °C, pH 6.0-10.0 and with 0.5-18.0% (w/v) NaCl. Respiratory quinones contained ubiquinone-9 and ubiquione-8 as major and minor components, respectively. Major fatty acids (> 10%) were summed feature 8 (C18:1ω6c and/or C18:1ω7c), summed feature 3 (C16:1ω6c and/or C16:1ω7c) and C16:0. Polar lipids included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, two unidentified phospholipids, one unidentified aminolipid, one unidentified glycolipid and four unidentified lipids. Strains MCT, PC and RC shared pairwise 16S rRNA gene sequence similarities of 99.9-100.0%, and showed higher similarities of 98.4-98.5% with Halomonas songnenensis NEAU-ST10-39T and 98.3-98.4% with Halomonas nanhaiensis YIM M 13059T than to other Halomonas type strains. Genomic comparisons revealed that those three strains had the pan-genome consisting of 4446 orthologous clusters, among which 676 orthologous clusters were absent in other Halomonas type strains. Phylogenomic tree indicated that strains MCT, PC and RC formed an independently stable clade with Halomonas nanhaiensis YIM M 13059T and Halomonas songnenensis NEAU-ST10-39T. The average nucleotide identity and digital DNA-DNA hybridization values between those three strains and other Halomonas type strains were < 89.9% and < 39.3%, respectively. Based upon phenotypic, chemotaxonomic, phylogenetic and genomic results, strains MCT, PC and RC represent a novel species in the genus Halomonas, for which the name Halomonas populi sp. nov. is proposed. The type strain is MCT (= JCM 33545T = MCCC 1K03942T).

RevDate: 2021-12-28

Almeida-Silva F, TM Venancio (2021)

Integration of genome-wide association studies and gene coexpression networks unveils promising soybean resistance genes against five common fungal pathogens.

Scientific reports, 11(1):24453.

Soybean is one of the most important legume crops worldwide. However, soybean yield is dramatically affected by fungal diseases, leading to economic losses of billions of dollars yearly. Here, we integrated publicly available genome-wide association studies and transcriptomic data to prioritize candidate genes associated with resistance to Cadophora gregata, Fusarium graminearum, Fusarium virguliforme, Macrophomina phaseolina, and Phakopsora pachyrhizi. We identified 188, 56, 11, 8, and 3 high-confidence candidates for resistance to F. virguliforme, F. graminearum, C. gregata, M. phaseolina and P. pachyrhizi, respectively. The prioritized candidate genes are highly conserved in the pangenome of cultivated soybeans and are heavily biased towards fungal species-specific defense responses. The vast majority of the prioritized candidate resistance genes are related to plant immunity processes, such as recognition, signaling, oxidative stress, systemic acquired resistance, and physical defense. Based on the number of resistance alleles, we selected the five most resistant accessions against each fungal species in the soybean USDA germplasm. Interestingly, the most resistant accessions do not reach the maximum theoretical resistance potential. Hence, they can be further improved to increase resistance in breeding programs or through genetic engineering. Finally, the coexpression network generated here is available in a user-friendly web application (https://soyfungigcn.venanciogroup.uenf.br/) and an R/Shiny package (https://github.com/almeidasilvaf/SoyFungiGCN) that serve as a public resource to explore soybean-pathogenic fungi interactions at the transcriptional level.

RevDate: 2021-12-28

Pérez-Duque A, Gonzalez-Muñoz A, Arboleda-Valencia J, et al (2021)

Comparative Genomics of Clinical and Environmental Isolates of Vibrio spp. of Colombia: Implications of Traits Associated with Virulence and Resistance.

Pathogens (Basel, Switzerland), 10(12): pii:pathogens10121605.

There is widespread concern about the increase in cases of human and animal infections caused by pathogenic Vibrio species due to the emergence of epidemic lineages. In Colombia, active surveillance by the National Institute of Health (INS) has confirmed the presence of Vibrio; however, in routine surveillance, these isolates are not genomically characterized. This study focused on the pangenome analysis of six Vibrio species: V. parahaemolyticus, V. vulnificus, V. alginolyticus, V. fluvialis, V. diabolicus and V. furnissii to determine the genetic architectures of potentially virulent and antimicrobial resistance traits. Isolates from environmental and clinical samples were genome sequenced, assembled and annotated. The most important species in public health were further characterized by multilocus sequence typing and phylogenomics. For V. parahaemolyticus, we found the virulent ST3 and ST120 genotypes. For V. vulnificus, we identified isolates belonging to lineages 1 and 2. Virulence gene homologues between species were found even in non-pathogenic species such as V. diabolicus. Annotations related to the mobilome, integrative mobile and conjugative elements and resistance genes were obtained from environmental and clinical isolates. This study contributes genomic information to the intensified surveillance program implemented by the INS to establish potential sources of vibriosis in Colombia.

RevDate: 2021-12-27

Son S, Lee R, Park SM, et al (2021)

Complete genome sequencing and comparative genomic analysis of Lactobacillus acidophilus C5 as a potential canine probiotics.

Journal of animal science and technology, 63(6):1411-1422.

Lactobacillus acidophilus is a gram-positive, microaerophilic, and acidophilic bacterial species. L. acidophilus strains in the gastrointestinal tracts of humans and other animals have been profiled, but strains found in the canine gut have not been studied yet. Our study helps in understanding the genetic features of the L. acidophilus C5 strain found in the canine gut, determining its adaptive features evolved to survive in the canine gut environment, and in elucidating its probiotic functions. To examine the canine L. acidophilus C5 genome, we isolated the C5 strain from a Korean dog and sequenced it using PacBio SMRT sequencing technology. A comparative genomic approach was used to assess genetic relationships between C5 and six other strains and study the distinguishing features related to different hosts. We found that most genes in the C5 strain were related to carbohydrate transport and metabolism. The pan-genome of seven L. acidophilus strains contained 2,254 gene families, and the core genome contained 1,726 gene families. The phylogenetic tree of the core genes in the canine L. acidophilus C5 strain was very close to that of two strains (DSM20079 and NCFM) from humans. We identified 30 evolutionarily accelerated genes in the L. acidophilus C5 strain in the ratio of non-synonymous to synonymous substitutions (dN/dS) analysis. Five of these thirty genes were associated with carbohydrate transport and metabolism. This study provides insights into genetic features and adaptations of the L. acidophilus C5 strain to survive the canine intestinal environment. It also suggests that the evolution of the L. acidophilus genome is closely related to the host's evolutionary adaptation process.

RevDate: 2021-12-27

Thomas P, Abdel-Glil MY, Subbaiyan A, et al (2021)

First Comparative Analysis of Clostridium septicum Genomes Provides Insights Into the Taxonomy, Species Genetic Diversity, and Virulence Related to Gas Gangrene.

Frontiers in microbiology, 12:771945.

Clostridium septicum is a Gram-positive, toxin-producing, and spore-forming bacterium that is recognized, together with C. perfringens, as the most important etiologic agent of progressive gas gangrene. Clostridium septicum infections are almost always fatal in humans and animals. Despite its clinical and agricultural relevance, there is currently limited knowledge of the diversity and genome structure of C. septicum. This study presents the complete genome sequence of C. septicum DSM 7534T type strain as well as the first comparative analysis of five C. septicum genomes. The taxonomy of C. septicum, as revealed by 16S rRNA analysis as well as by genomic wide indices such as protein-based phylogeny, average nucleotide identity, and digital DNA-DNA hybridization indicates a stable clade. The composition and presence of prophages, CRISPR elements and accessory genetic material was variable in the investigated genomes. This is in contrast to the limited genetic variability described for the phylogenetically and phenotypically related species Clostridium chauvoei. The restriction-modification (RM) systems between two C. septicum genomes were heterogeneous for the RM types they encoded. C. septicum has an open pangenome with 2,311 genes representing the core genes and 1,429 accessory genes. The core genome SNP divergence between genome pairs varied up to 4,886 pairwise SNPs. A vast arsenal of potential virulence genes was detected in the genomes studied. Sequence analysis of these genes revealed that sialidase, hemolysin, and collagenase genes are conserved compared to the α-toxin and hyaluronidase genes. In addition, a conserved gene found in all C. septicum genomes was predicted to encode a leucocidin homolog (beta-channel forming cytolysin) similar (71.10% protein identity) to Clostridium chauvoei toxin A (CctA), which is a potent toxin. In conclusion, our results provide first, valuable insights into strain relatedness and genomic plasticity of C. septicum and contribute to our understanding of the virulence mechanisms of this important human and animal pathogen.

RevDate: 2021-12-24

Decano AG, Pettigrew K, Sabiiti W, et al (2021)

Pan-Resistome Characterization of Uropathogenic Escherichia coli and Klebsiella pneumoniae Strains Circulating in Uganda and Kenya, Isolated from 2017-2018.

Antibiotics (Basel, Switzerland), 10(12): pii:antibiotics10121547.

Urinary tract infection (UTI) develops after a pathogen adheres to the inner lining of the urinary tract. Cases of UTIs are predominantly caused by several Gram-negative bacteria and account for high morbidity in the clinical and community settings. Of greater concern are the strains carrying antimicrobial resistance (AMR)-conferring genes. The gravity of a UTI is also determined by a spectrum of other virulence factors. This study represents a pilot project to investigate the burden of AMR among uropathogens in East Africa. We examined bacterial samples isolated in 2017-2018 from in- and out-patients in Kenya (KY) and Uganda (UG) that presented with clinical symptoms of UTI. We reconstructed the evolutionary history of the strains, investigated their population structure, and performed comparative analysis their pangenome contents. We found 55 Escherichia coli and 19 Klebsiella pneumoniae strains confirmed uropathogenic following screening for the prevalence of UTI virulence genes including fimH, iutA, feoA/B/C, mrkD, and foc. We identified 18 different sequence types in E. coli population while all K. pneumoniae strains belong to ST11. The most prevalent E. coli sequence types were ST131 (26%), ST335/1193 (10%), and ST10 (6%). Diverse plasmid types were observed in both collections such as Incompatibility (IncF/IncH/IncQ1/IncX4) and Col groups. Pangenome analysis of each set revealed a total of 2862 and 3464 genes comprised the core genome of E. coli and K. pneumoniae population, respectively. Among these are acquired AMR determinants including fluoroquinolone resistance-conferring genes aac(3)-Ib-cr and other significant genes: aad, tet, sul1, sul2, and cat, which are associated with aminoglycoside, tetracycline, sulfonamide, and chloramphenicol resistance, respectively. Accessory genomes of both species collections were detected several β-lactamase genes, blaCTX-M, blaTEM and blaOXA, or blaNDM. Overall, 93% are multi-drug resistant in the E. coli collection while 100% of the K. pneumoniae strains contained genes that are associated with resistance to three or more antibiotic classes. Our findings illustrate the abundant acquired resistome and virulome repertoire in uropathogenic E. coli and K. pneumoniae, which are mainly disseminated via clonal and horizontal transfer, circulating in the East African region. We further demonstrate here that routine genomic surveillance is necessary for high-resolution bacterial epidemiology of these important AMR pathogens.

RevDate: 2021-12-17

Yi B, AH Dalpke (2021)

Revisiting the intrageneric structure of the genus Pseudomonas with complete whole genome sequence information: Insights into diversity and pathogen-related genetic determinants.

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases pii:S1567-1348(21)00483-4 [Epub ahead of print].

Pseudomonas spp. exhibit considerable differences in host specificity and virulence. Most Pseudomonas species were isolated exclusively from environmental sources, ranging from soil to plants, but some Pseudomonas species have been detected from versatile sources, including both human host and environmental sources. Understanding genome variations that generate the tremendous diversity in Pseudomonas biology is important in controlling the incidence of infections. With a data set of 704 Pseudomonas complete whole genome sequences representing 186 species, Pseudomonas intrageneric structure was investigated by hierarchical clustering based on average nucleotide identity, and by phylogeny analysis based on concatenated core-gene alignment. Further comparative functional analyses indicated that Pseudomonas species only living in natural habitats lack multiple functions that are important in the regulation of bacterial pathogenesis, indicating the possession of these functions might be characteristic of Pseudomonas human pathogens. Moreover, we have performed pan-genome based homogeneity analyses, and detected genes with conserved structures but diversified functions across the Pseudomonas genomes, suggesting these genes play a role in driving diversity. In summary, this study provided insights into the dynamics of genome diversity and pathogen-related genetic determinants in Pseudomonas, which might help the development of more targeted antibiotics for the treatment of Pseudomonas infections.

RevDate: 2021-12-17

Lian X, Zhang H, Jiang C, et al (2021)

De novo chromosome-level genome of a semi-dwarf cultivar of Prunus persica identifies the aquaporin PpTIP2 as responsible for temperature-sensitive semi-dwarf trait and PpB3-1 for flower type and size.

Plant biotechnology journal [Epub ahead of print].

Peach (Prunus persica) is one of the most important fruit crops globally, but its cultivation can be hindered by large tree size. 'Zhongyoutao 14' (CN14) is a temperature-sensitive semi-dwarf (TSSD) cultivar which might be useful as breeding stock. The genome of CN14 was sequenced and assembled de novo using single-molecule real-time sequencing and chromosome conformation capture assembly. A high-quality genome was assembled and annotated, with 228.82 Mb mapped to eight chromosomes. Eighty-six re-sequenced F1 individuals and 334 previously re-sequenced accessions were used to identify candidate genes controlling TSSD and flower type and size. An aquaporin tonoplast intrinsic protein (PpTIP2) was a strong candidate gene for control of TSSD. Sequence variations in the upstream regulatory region of PpTIP2 correlated with different transcriptional activity at different temperatures. PpB3-1, a candidate gene for flower type (SH) and flower size, contributed to petal development and promoted petal enlargement. The locus of another twelve agronomic traits were identified through genome-wide association study. Most of these loci exhibited consistent and precise association signals, except for flesh texture and flesh adhesion. A 6015-bp insertion in exon 3 and a 26-bp insertion upstream of PpMYB25 were associated with fruit hairless. Along with a 70.5-Kb gap at the F-M locus in CN14, another two new alleles were identified in peach accessions. Our findings will not only promote genomic research and agronomic breeding in peach, but also provide a foundation for the peach pan-genome.

RevDate: 2021-12-20
CmpDate: 2021-12-20

Anjos WF, Lanes GC, Azevedo VA, et al (2021)

GENPPI: standalone software for creating protein interaction networks from genomes.

BMC bioinformatics, 22(1):596.

BACKGROUND: Bacterial genomes are being deposited into online databases at an increasing rate. Genome annotation represents one of the first efforts to understand organisms and their diseases. Some evolutionary relationships capable of being annotated only from genomes are conserved gene neighbourhoods (CNs), phylogenetic profiles (PPs), and gene fusions. At present, there is no standalone software that enables networks of interactions among proteins to be created using these three evolutionary characteristics with efficient and effective results.

RESULTS: We developed GENPPI software for the ab initio prediction of interaction networks using predicted proteins from a genome. In our case study, we employed 50 genomes of the genus Corynebacterium. Based on the PP relationship, GENPPI differentiated genomes between the ovis and equi biovars of the species Corynebacterium pseudotuberculosis and created groups among the other species analysed. If we inspected only the CN relationship, we could not entirely separate biovars, only species. Our software GENPPI was determined to be efficient because, for example, it creates interaction networks from the central genomes of 50 species/lineages with an average size of 2200 genes in less than 40 min on a conventional computer. Moreover, the interaction networks that our software creates reflect correct evolutionary relationships between species, which we confirmed with average nucleotide identity analyses. Additionally, this software enables the user to define how he or she intends to explore the PP and CN characteristics through various parameters, enabling the creation of customized interaction networks. For instance, users can set parameters regarding the genus, metagenome, or pangenome. In addition to the parameterization of GENPPI, it is also the user's choice regarding which set of genomes they are going to study.

CONCLUSIONS: GENPPI can help fill the gap concerning the considerable number of novel genomes assembled monthly and our ability to process interaction networks considering the noncore genes for all completed genome versions. With GENPPI, a user dictates how many and how evolutionarily correlated the genomes answer a scientific query.

RevDate: 2021-12-15

Zhao S, Zhang C, Rogers MJ, et al (2021)

Differentiating closely affiliated Dehalococcoides lineages by a novel genetic marker identified via computational pangenome analysis.

Applied and environmental microbiology [Epub ahead of print].

As a group, Dehalococcoides dehalogenate a wide range of organohalide pollutants but the range of organohalide compounds that can be utilized for reductive dehalogenation differs among the Dehalococcoides strains. Dehalococcoides lineages cannot be reliably disambiguated in mixed communities using typical phylogenetic markers, which often confounds bioremediation efforts. Here, we describe a computational approach to identify Dehalococcoides genetic markers with improved discriminatory resolution. Screening core genes from the Dehalococcoides pangenome for degree of similarity and frequency of 100% identity found a candidate genetic marker encoding a bacterial neuraminidase repeat (BNR)-containing protein of unknown function. This gene exhibits the fewest completely identical amino acid sequences and among the lowest average amino acid sequence identity in the core pangenome. Primers targeting BNR could effectively discriminate between 40 available BNR sequences (in silico) and 10 different Dehalococcoides isolates (in vitro). Amplicon sequencing of BNR fragments generated from 22 subsurface soil samples revealed a total of 109 amplicon sequence variants, suggesting a high diversity of Dehalococcoides distributed in environment. Therefore, the BNR gene can serve as an alternative genetic marker to differentiate strains of Dehalococcoides in complicated microbial communities. Importance The challenge of discriminating between phylogenetically similar but functionally distinct bacterial lineages is particularly relevant to the development of technologies seeking to exploit the metabolic or physiological characteristics of specific members of bacterial genera. A computational approach was developed to expedite screening of potential genetic markers among phylogenetically affiliated bacteria. Using this approach, a gene encoding a bacterial neuraminidase repeat (BNR)-containing protein of unknown function was selected and evaluated as a genetic marker to differentiate strains of Dehalococcoides, an environmentally relevant genus of bacteria whose members can transform and detoxify a range of halogenated organic solvents and persistent organic pollutants, in complex microbial communities to demonstrate the validity of the approach. Moreover, many apparently phylogenetically distinct, currently uncharacterized Dehalococcoides were detected in environmental samples derived from contaminated sites.

RevDate: 2021-12-14

Zanini SF, Bayer PE, Wells R, et al (2021)

Pangenomics in crop improvement-from coding structural variations to finding regulatory variants with pangenome graphs.

The plant genome [Epub ahead of print].

Since the first reported crop pangenome in 2014, advances in high-throughput and cost-effective DNA sequencing technologies facilitated multiple such studies including the pangenomes of oilseed rape (Brassica napus L.), soybean [Glycine max (L.) Merr.], rice (Oryza sativa L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). Compared with single-reference genomes, pangenomes provide a more accurate representation of the genetic variation present in a species. By combining the genomic data of multiple accessions, pangenomes allow for the detection and annotation of complex DNA polymorphisms such as structural variations (SVs), one of the major determinants of genetic diversity within a species. In this review we summarize the current literature on crop pangenomics, focusing on their application to find candidate SVs involved in traits of agronomic interest. We then highlight the potential of pangenomes in the discovery and functional characterization of noncoding regulatory sequences and their variations. We conclude with a summary and outlook on innovative data structures representing the complete content of plant pangenomes including annotations of coding and noncoding elements and outcomes of transcriptomic and epigenomic experiments.

RevDate: 2021-12-13

Pronozin AY, Bragina MK, EA Salina (2021)

Crop pangenomes.

Vavilovskii zhurnal genetiki i selektsii, 25(1):57-63.

Progress in genome sequencing, assembly and analysis allows for a deeper study of agricultural plants' chromosome structures, gene identification and annotation. The published genomes of agricultural plants proved to be a valuable tool for studing gene functions and for marker-assisted and genomic selection. However, large structural genome changes, including gene copy number variations (CNVs) and gene presence/absence variations (PAVs), prevail in crops. These genomic variations play an important role in the functional set of genes and the gene composition in individuals of the same species and provide the genetic determination of the agronomically important crops properties. A high degree of genomic variation observed indicates that single reference genomes do not represent the diversity within a species, leading to the pangenome concept. The pangenome represents information about all genes in a taxon: those that are common to all taxon members and those that are variable and are partially or completely specific for particular individuals. Pangenome sequencing and analysis technologies provide a large-scale study of genomic variation and resources for an evolutionary research, functional genomics and crop breeding. This review provides an analysis of agricultural plants' pangenome studies. Pangenome structural features, methods and programs for bioinformatic analysis of pangenomic data are described.

RevDate: 2021-12-13

Zimin AV, Shumate A, Shinder I, et al (2021)

A reference-quality, fully annotated genome from a Puerto Rican individual.

Genetics pii:6460343 [Epub ahead of print].

Until 2019, the human genome was available in only one fully-annotated version, GRCh38, which was the result of 18 years of continuous improvement and revision. Despite dramatic improvements in sequencing technology, no other genome was available as an annotated reference until 2019, when the genome of an Ashkenazi individual, Ash1, was released. In this study, we describe the assembly and annotation of a second individual genome, from a Puerto Rican individual whose DNA was collected as part of the Human Pangenome project. The new genome, called PR1, is the first true reference genome created from an individual of African descent. Due to recent improvements in both sequencing and assembly technology, and particularly to the use of the recently completed CHM13 human genome as a guide to assembly, PR1 is more complete and more contiguous than either GRCh38 or Ash1. Annotation revealed 37,755 genes (of which 19,999 are protein-coding), including 12 additional gene copies that are present in PR1 and missing from CHM13. 57 genes have fewer copies in PR1 than in CHM13, 9 map only partially, and 3 genes (all non-coding) from CHM13 are entirely missing from PR1.

RevDate: 2021-12-13

Gautreau G, Bazin A, Gachet M, et al (2021)

Correction: PPanGGOLiN: Depicting microbial diversity via a partitioned pangenome graph.

PLoS computational biology, 17(12):e1009687 pii:PCOMPBIOL-D-21-02143.

[This corrects the article DOI: 10.1371/journal.pcbi.1007732.].

RevDate: 2021-12-13

Siani R, Stabl G, Gutjahr C, et al (2021)

Acidovorax pan-genome reveals specific functional traits for plant beneficial and pathogenic plant-associations.

Microbial genomics, 7(12):.

Beta-proteobacteria belonging to the genus Acidovorax have been described from various environments. Many strains can interact with a range of hosts, including humans and plants, forming neutral, beneficial or detrimental associations. In the frame of this study, we investigated the genomic properties of 52 bacterial strains of the genus Acidovorax, isolated from healthy roots of Lotus japonicus, with the intent of identifying traits important for effective plant-growth promotion. Based on single-strain inoculation bioassays with L. japonicus, performed in a gnotobiotic system, we distinguished seven robust plant-growth promoting strains from strains with no significant effects on plant-growth. We showed that the genomes of the two groups differed prominently in protein families linked to sensing and transport of organic acids, production of phytohormones, as well as resistance and production of compounds with antimicrobial properties. In a second step, we compared the genomes of the tested isolates with those of plant pathogens and free-living strains of the genus Acidovorax sourced from public repositories. Our pan-genomics comparison revealed features correlated with commensal and pathogenic lifestyle. We showed that commensals and pathogens differ mostly in their ability to use plant-derived lipids and in the type of secretion-systems being present. Most free-living Acidovorax strains did not harbour any secretion-systems. Overall, our data indicate that Acidovorax strains undergo extensive adaptations to their particular lifestyle by horizontal uptake of novel genetic information and loss of unnecessary genes.

RevDate: 2021-12-10

Conrad RE, Viver T, Gago JF, et al (2021)

Toward quantifying the adaptive role of bacterial pangenomes during environmental perturbations.

The ISME journal [Epub ahead of print].

Metagenomic surveys have revealed that natural microbial communities are predominantly composed of sequence-discrete, species-like populations but the genetic and/or ecological processes that maintain such populations remain speculative, limiting our understanding of population speciation and adaptation to perturbations. To address this knowledge gap, we sequenced 112 Salinibacter ruber isolates and 12 companion metagenomes from four adjacent saltern ponds in Mallorca, Spain that were experimentally manipulated to dramatically alter salinity and light intensity, the two major drivers of this ecosystem. Our analyses showed that the pangenome of the local Sal. ruber population is open and similar in size (~15,000 genes) to that of randomly sampled Escherichia coli genomes. While most of the accessory (noncore) genes were isolate-specific and showed low in situ abundances based on the metagenomes compared to the core genes, indicating that they were functionally unimportant and/or transient, 3.5% of them became abundant when salinity (but not light) conditions changed and encoded for functions related to osmoregulation. Nonetheless, the ecological advantage of these genes, while significant, was apparently not strong enough to purge diversity within the population. Collectively, our results provide an explanation for how this immense intrapopulation gene diversity is maintained, which has implications for the prokaryotic species concept.

RevDate: 2021-12-10

Jalal K, Khan K, Ahmad D, et al (2021)

Pan-Genome Reverse Vaccinology Approach for the Design of Multi-Epitope Vaccine Construct against Escherichia albertii.

International journal of molecular sciences, 22(23): pii:ijms222312814.

Escherichia albertii is characterized as an emerging pathogen, causing enteric infections. It is responsible for high mortality rate, especially in children, elderly, and immunocompromised people. To the best of our knowledge, no vaccine exists to curb this pathogen. Therefore, in current study, we aimed to identify potential vaccine candidates and design chimeric vaccine models against Escherichia albertii from the analysis of publicly available data of 95 strains, using a reverse vaccinology approach. Outer-membrane proteins (n = 4) were identified from core genome as vaccine candidates. Eventually, outer membrane Fimbrial usher (FimD) protein was selected as a promiscuous vaccine candidate and utilized to construct a potential vaccine model. It resulted in three epitopes, leading to the design of twelve vaccine constructs. Amongst these, V6 construct was found to be highly immunogenic, non-toxic, non-allergenic, antigenic, and most stable. This was utilized for molecular docking and simulation studies against six HLA and two TLR complexes. This construct can therefore be used for pan-therapy against different strains of E. albertii and needs to be tested in vitro and in vivo.

RevDate: 2021-12-08

Bohr LL, Youngblom MA, Eldholm V, et al (2021)

Genome reorganization during emergence of host-associated Mycobacterium abscessus.

Microbial genomics, 7(12):.

Mycobacterium abscessus is a rapid growing, free-living species of bacterium that also causes lung infections in humans. Human infections are usually acquired from the environment; however, dominant circulating clones (DCCs) have emerged recently in both M. abscessus subsp. massiliense and subsp. abscessus that appear to be transmitted among humans and are now globally distributed. These recently emerged clones are potentially informative about the ecological and evolutionary mechanisms of pathogen emergence and host adaptation. The geographical distribution of DCCs has been reported, but the genomic processes underlying their transition from environmental bacterium to human pathogen are not well characterized. To address this knowledge gap, we delineated the structure of M. abscessus subspecies abscessus and massiliense using genomic data from 200 clinical isolates of M. abscessus from seven geographical regions. We identified differences in overall patterns of lateral gene transfer (LGT) and barriers to LGT between subspecies and between environmental and host-adapted bacteria. We further characterized genome reorganization that accompanied bacterial host adaptation, inferring selection pressures acting at both genic and intergenic loci. We found that both subspecies encode an expansive pangenome with many genes at rare frequencies. Recombination appears more frequent in M. abscessus subsp. massiliense than in subsp. abscessus, consistent with prior reports. We found evidence suggesting that phage are exchanged between subspecies, despite genetic barriers evident elsewhere throughout the genome. Patterns of LGT differed according to niche, with less LGT observed among host-adapted DCCs versus environmental bacteria. We also found evidence suggesting that DCCs are under distinct selection pressures at both genic and intergenic sites. Our results indicate that host adaptation of M. abscessus was accompanied by major changes in genome evolution, including shifts in the apparent frequency of LGT and impacts of selection. Differences were evident among the DCCs as well, which varied in the degree of gene content remodelling, suggesting they were placed differently along the evolutionary trajectory toward host adaptation. These results provide insight into the evolutionary forces that reshape bacterial genomes as they emerge into the pathogenic niche.

RevDate: 2021-12-06

Lata KS, Kumar S, Vindal V, et al (2021)

A core and pan gene map of Leptospira genus and its interactions with human host.

Microbial pathogenesis pii:S0882-4010(21)00621-5 [Epub ahead of print].

Leptospira species are the etiological agent of an emerging zoonotic disease known as "Leptospirosis" that substantially affects both human health and economy across the globe. Despite the global importance of the disease, pathogenetic features, host-adaptation and proper diagnosis of this bacteria remains lacking. To accomplish these gaps, pan-genome of Leptospira genus was explored in the present study. The pan-genome of Leptospira genus was comprised of core (692) and variable parts (softcore:1804, shell:6432, cloud:16,600). The functional analysis revealed the abundancy of "Translation, ribosomal structure and biogenesis" COG class in core-genes; whereas in accessory parts, genes involved in signal transduction was the most abundant. Furthermore, pathogen-host interaction (PHI) analysis of core and accessory proteins with human proteins showed the presence of a total of 599 and 510 interactions, respectively. There were eight hubs in core PHI network and five hubs in PHI network of accessory proteins. The human's proteins involved in these interactions were found functionally enriched in metabolic processes, responses to stimulus and immune system processes. Further, pan-genome based phylogeny separated the Leptospira genus in three major clades (belonging to P1, P2 and S) which relates with their pathogenicity level. Additionally, pathogenic and saprophytic clade specific genes of Leptospira have also been identified and functionally annotated for COG, KEGG and virulence factors. The results revealed the presence of 102 pathogenic and 215 saprophytic group specific gene clusters. The COG functional annotation of pathogen specific genes showed that defence mechanism followed by signal transduction mechanisms category was most significantly enriched COG category; whereas in saprophytic group, signal transduction mechanisms was the most abundant COG, suggesting their role in adaptation and hence important for microbe's evolution and survival. In conclusion, this study provides a new insight of genomic features of Leptospira genus which may further be implemented for development of better control actions of the disease.

RevDate: 2021-12-06

Lin S, Sun B, Shi X, et al (2021)

Comparative Genomic and Pan-Genomic Characterization of Staphylococcus epidermidis From Different Sources Unveils the Molecular Basis and Potential Biomarkers of Pathogenic Strains.

Frontiers in microbiology, 12:770191.

Coagulase-negative Staphylococcus (CoNS) is the most common pathogen causing traumatic endophthalmitis. Among which, Staphylococcus epidermidis is the most common species that colonizes human skin, eye surfaces, and nasal cavity. It is also the main cause of nosocomial infection, specially foreign body-related bloodstream infections (FBR-BSIs). Although some studies have reported the genome characteristics of S. epidermidis, the genome of ocular trauma-sourced S. epidermidis strain and a comprehensive understanding of its pathogenicity are still lacking. Our study sequenced, analyzed, and reported the whole genomes of 11 ocular trauma-sourced samples of S. epidermidis that caused traumatic endophthalmitis. By integrating publicly available genomes, we obtained a total of 187 S. epidermidis samples from healthy and diseased eyes, skin, respiratory tract, and blood. Combined with pan-genome, phylogenetic, and comparative genomic analyses, our study showed that S. epidermidis, regardless of niche source, exhibits two founder lineages with different pathogenicity. Moreover, we identified several potential biomarkers associated with the virulence of S. epidermidis, including essD, uhpt, sdrF, sdrG, fbe, and icaABCDR. EssD and uhpt have high homology with esaD and hpt in Staphylococcus aureus, showing that the genomes of S. epidermidis and S. aureus may have communicated during evolution. SdrF, sdrG, fbe, and icaABCDR are related to biofilm formation. Compared to S. epidermidis from blood sources, ocular-sourced strains causing intraocular infection had no direct relationship with biofilm formation. In conclusion, this study provided additional data resources for studies on S. epidermidis and improved our understanding of the evolution and pathogenicity among strains of different sources.

RevDate: 2021-12-06

Wu S, Pang R, Huang J, et al (2021)

Evolutionary Divergence of the Novel Staphylococcal Species Staphylococcus argenteus.

Frontiers in microbiology, 12:769642.

Currently, invasive infections caused by Staphylococcus argenteus, which is a recently named staphylococcal species, are increasingly reported worldwide. However, only a few genomic studies of S. argenteus have offered comprehensive information regarding its genetic diversity, epidemiological characteristics, antimicrobial resistance genes (ARGs), virulence genes and other profiles. Here, we describe a comparative genomic analysis by population structure, pangenome, panmobilome, region-specific accessory genes confer an adaptive advantage in 153 S. argenteus strains which comprised 24 strains sequenced in this study and 129 strains whose genome sequences were available from GenBank. As a result, the population of S. argenteus comprised seven genetically distinct clades, including two major clades (C1 and C2), with distinct isolation source patterns. Pangenome analysis revealed that S. argenteus has an open pangenome composed of 7,319 genes and a core genome composed of 1,508 genes. We further determined the distributions of 75 virulence factors (VFs) and 30 known ARGs and identified at least four types of plasmids and 93 complete or partial putative prophages. It indicate that S. argenteus may show a similar level of pathogenicity to that of S. aureus. This study also provides insights into the evolutionary divergence of this pathogen, indicating that the geographical distribution was a potential driving force behind the evolutionary divergence of S. argenteus. The preferential horizontal acquisition of particular elements, such as staphylococcal cassette chromosome mec elements and plasmids, was observed in specific regions, revealing potential gene exchange between S. argenteus strains and local S. aureus strains. Moreover, multiple specific genes related to environmental adaptation were identified in strains isolated from East Asia. However, these findings may help promote our understanding of the evolutionary divergence of this bacterium at a high genetic resolution by providing insights into the epidemiology of S. argenteus and may help combat its spread.

RevDate: 2021-12-06

Bohra A, Bansal KC, A Graner (2021)

The 3366 chickpea genomes for research and breeding.

Trends in plant science pii:S1360-1385(21)00323-X [Epub ahead of print].

Genome sequences provide an unprecedented resource to rapidly develop modern crops. A recent paper by Varshney et al. provides genome variation maps of 3366 chickpea accessions. Here, we highlight how this breakthrough research can fundamentally change breeding practices of chickpea and potentially other crops.

RevDate: 2021-12-01

Noshay JM, Liang Z, Zhou P, et al (2021)

Stability of DNA methylation and chromatin accessibility in structurally diverse maize genomes.

G3 (Bethesda, Md.), 11(8):.

Accessible chromatin and unmethylated DNA are associated with many genes and cis-regulatory elements. Attempts to understand natural variation for accessible chromatin regions (ACRs) and unmethylated regions (UMRs) often rely upon alignments to a single reference genome. This limits the ability to assess regions that are absent in the reference genome assembly and monitor how nearby structural variants influence variation in chromatin state. In this study, de novo genome assemblies for four maize inbreds (B73, Mo17, Oh43, and W22) are utilized to assess chromatin accessibility and DNA methylation patterns in a pan-genome context. A more complete set of UMRs and ACRs can be identified when chromatin data are aligned to the matched genome rather than a single reference genome. While there are UMRs and ACRs present within genomic regions that are not shared between genotypes, these features are 6- to 12-fold enriched within regions between genomes. Characterization of UMRs present within shared genomic regions reveals that most UMRs maintain the unmethylated state in other genotypes with only ∼5% being polymorphic between genotypes. However, the majority (71%) of UMRs that are shared between genotypes only exhibit partial overlaps suggesting that the boundaries between methylated and unmethylated DNA are dynamic. This instability is not solely due to sequence variation as these partially overlapping UMRs are frequently found within genomic regions that lack sequence variation. The ability to compare chromatin properties among individuals with structural variation enables pan-epigenome analyses to study the sources of variation for accessible chromatin and unmethylated DNA.

RevDate: 2021-12-01

Brockhurst MA, E Harrison (2021)

Ecological and evolutionary solutions to the plasmid paradox.

Trends in microbiology pii:S0966-842X(21)00267-5 [Epub ahead of print].

The 'plasmid paradox' arises because, although plasmids are common features of bacterial genomes, theoretically they should not exist: rates of conjugation were believed insufficient to allow plasmids to persist by infectious transmission, whereas the costs of plasmid maintenance meant that plasmids should be purged by negative selection regardless of whether they encoded beneficial accessory traits because these traits should eventually be captured by the chromosome, enabling the loss of the redundant plasmid. In the decade since the plasmid paradox was described, new data and theory show that a range of ecological and evolutionary mechanisms operate in bacterial populations and communities to explain the widespread distribution and stable maintenance of plasmids. We conclude, therefore, that multiple solutions to the plasmid paradox are now well understood. The current challenge for the field, however, is to better understand how these solutions operate in natural bacterial communities to explain and predict the distribution of plasmids and the dynamics of the horizontal gene transfer that they mediate in bacterial (pan)genomes.

RevDate: 2021-11-30

Wang Z, Zheng X, Guo G, et al (2021)

Combining pangenome analysis to identify potential cross-protective antigens against avian pathogenic Escherichia coli.

Avian pathology : journal of the W.V.P.A [Epub ahead of print].

AbstractAvian pathogenic Escherichia coli (APEC) is the bacterial pathogen of poultry colibacillosis, which causes significant economic losses to the poultry industry. The lack of an effective vaccine against multiple serotypes and the emergence of multi-resistant isolates have made the control of avian colibacillosis troublesome. To identify conserved potential vaccine candidates, 58 genomes of APEC were obtained (54 sequenced by our laboratory and 4 downloaded from NCBI). A reverse vaccinology (RV) method based on the pangenome - called Pan-RV analysis - was performed in APEC-protective protein mining for the first time. Finally, four proteins were selected, and their immunoreactivity with anti-O1, O2, and O78 serum was verified by western blotting. Our in silico method of analysis will pave the way for rapid screening of vaccine candidates and will lay the foundation for the development of a highly effective subunit vaccine controlling APEC infection.

RevDate: 2021-11-29

Saha O, Islam MR, Rahman MS, et al (2021)

First report from Bangladesh on genetic diversity of multidrug-resistant Pasteurella multocida type B:2 in fowl cholera.

Veterinary world, 14(9):2527-2542.

Background and Aim: Fowl cholera (FC) caused by Pasteurella multocida is a highly contagious bacterial disease of global importance for poultry production. The severity and incidence of FC caused by P. multocida may vary considerably depending on several factors associated with the host (including species and age of infected birds), the environment, and the bacterial strain. This study aimed to investigate the genetic diversity of multidrug-resistant P. multocida strains isolated from FC outbreaks in laying hens from commercial farms of Bangladesh.

Materials and Methods: We collected 57 samples of suspected FC, including 36 live and 21 dead laying hens. P. multocida isolates were characterized by biochemical and molecular-biological methods.

Results: Twenty-two strains of P. multocida were isolated from these samples through phenotypic and genotypic characterization. The strains were grouped into two distinct random amplification of polymorphic DNA (RAPD) biotypes harboring a range of pathogenic genes; exbB, ompH, ptfA, nanB, sodC, and hgbA. In this study, 90.90% and 81.82% P. multocida strains were multidrug-resistant and biofilm formers, respectively. Whole-genome sequencing of the two representative RAPD phylotypes confirmed as P. multocida type B: L2:ST122, harboring a number of virulence factors-associated genes (VFGs), and antimicrobial resistance (AMR) genes (ARGs). In addition, pan-genome analysis revealed 90 unique genes in the genomes of P. multocida predicted to be associated with versatile metabolic functions, pathogenicity, virulence, and AMR.

Conclusion: This is first-ever report on the association of P. multocida genotype B: L2:ST122 and related VFGs and ARGs in the pathogenesis of FC in laying hens. This study also provides a genetic context for future researches on the evolutionary diversity of P. multocida strains and their host adaptation.

RevDate: 2021-11-29

Hall JPJ, Botelho J, Cazares A, et al (2022)

What makes a megaplasmid?.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 377(1842):20200472.

Naturally occurring plasmids come in different sizes. The smallest are less than a kilobase of DNA, while the largest can be over three orders of magnitude larger. Historically, research has tended to focus on smaller plasmids that are usually easier to isolate, manipulate and sequence, but with improved genome assemblies made possible by long-read sequencing, there is increased appreciation that very large plasmids-known as megaplasmids-are widespread, diverse, complex, and often encode key traits in the biology of their host microorganisms. Why are megaplasmids so big? What other features come with large plasmid size that could affect bacterial ecology and evolution? Are megaplasmids 'just' big plasmids, or do they have distinct characteristics? In this perspective, we reflect on the distribution, diversity, biology, and gene content of megaplasmids, providing an overview to these large, yet often overlooked, mobile genetic elements. This article is part of the theme issue 'The secret lives of microbial mobile genetic elements'.

RevDate: 2021-11-27

Hwang Y, Schulze-Makuch D, Arens FL, et al (2021)

Leave no stone unturned: individually adapted xerotolerant Thaumarchaeota sheltered below the boulders of the Atacama Desert hyperarid core.

Microbiome, 9(1):234.

BACKGROUND: The hyperarid core of the Atacama Desert is an extremely harsh environment thought to be colonized by only a few heterotrophic bacterial species. Current concepts for understanding this extreme ecosystem are mainly based on the diversity of these few species, yet a substantial area of the Atacama Desert hyperarid topsoil is covered by expansive boulder accumulations, whose underlying microbiomes have not been investigated so far. With the hypothesis that these sheltered soils harbor uniquely adapted microbiomes, we compared metagenomes and geochemistry between soils below and beside boulders across three distantly located boulder accumulations in the Atacama Desert hyperarid core.

RESULTS: Genome-resolved metagenomics of eleven samples revealed substantially different microbial communities in soils below and beside boulders, despite the presence of shared species. Archaea were found in significantly higher relative abundance below the boulders across all samples within distances of up to 205 km. These key taxa belong to a novel genus of ammonia-oxidizing Thaumarchaeota, Candidatus Nitrosodeserticola. We resolved eight mid-to-high quality genomes of this genus and used comparative genomics to analyze its pangenome and site-specific adaptations. Ca. Nitrosodeserticola genomes contain genes for ammonia oxidation, the 3-hydroxypropionate/4-hydroxybutyrate carbon fixation pathway, and acetate utilization indicating a chemolithoautotrophic and mixotrophic lifestyle. They also possess the capacity for tolerating extreme environmental conditions as highlighted by the presence of genes against oxidative stress and DNA damage. Site-specific adaptations of the genomes included the presence of additional genes for heavy metal transporters, multiple types of ATP synthases, and divergent genes for aquaporins.

CONCLUSION: We provide the first genomic characterization of hyperarid soil microbiomes below the boulders in the Atacama Desert, and report abundant and highly adapted Thaumarchaeaota with ammonia oxidation and carbon fixation potential. Ca. Nitrosodeserticola genomes provide the first metabolic and physiological insight into a thaumarchaeal lineage found in globally distributed terrestrial habitats characterized by various environmental stresses. We consequently expand not only the known genetic repertoire of Thaumarchaeota but also the diversity and microbiome functioning in hyperarid ecosystems. Video Abstract.

RevDate: 2021-11-27

Pardo-Esté C, Lorca D, Castro-Severyn J, et al (2021)

Genetic Characterization of Salmonella Infantis with Multiple Drug Resistance Profiles Isolated from a Poultry-Farm in Chile.

Microorganisms, 9(11): pii:microorganisms9112370.

Salmonella comprises over 2500 serotypes and foodborne contamination associated with this pathogen remains an important health concern worldwide. During the last decade, a shift in serotype prevalence has occurred as traditionally less prevalent serotypes are increasing in frequency of infections, especially those related to poultry meat contamination. S. Infantis is one of the major emerging serotypes, and these strains commonly display antimicrobial resistance and can persist despite cleaning protocols. Thus, this work aimed to isolate S. Infantis strains from a poultry meat farm in Santiago, Chile and to characterize genetic variations present in them. We determined their genomic and phenotypic profiles at different points along the production line. The results indicate that the strains encompass 853 polymorphic sites (core-SNPs) with isolates differing from one another by 0-347 core SNPs, suggesting variation among them; however, we found discrete correlations with the source of the sample in the production line. Furthermore, the pan-genome was composed of 4854 total gene clusters of which 2618 (53.9%) corresponds to the core-genome and only 181 (3.7%) are unique genes (those present in one particular strain). This preliminary analysis will enrich the surveillance of Salmonella, yet further studies are required to assess their evolution and phylogeny.

RevDate: 2021-11-27

Kim E, Yang SM, Won JE, et al (2021)

Real-Time PCR Method for the Rapid Detection and Quantification of Pathogenic Staphylococcus Species Based on Novel Molecular Target Genes.

Foods (Basel, Switzerland), 10(11): pii:foods10112839.

Coagulase-positive Staphylococcus aureus is a foodborne pathogen considered one of the causes of food-related disease outbreaks. Like S. aureus, Staphylococcus capitis, Staphylococcus caprae, and S. epidermidis are opportunistic pathogens causing clinical infections and food contamination. The objective of our study was to develop a rapid, accurate, and monitoring technique to detect four Staphylococcus species in food. Four novel molecular targets (GntR family transcriptional regulator for S. aureus, phosphomannomutase for S. epidermidis, FAD-dependent urate hydroxylase for S. capitis, and Gram-positive signal peptide protein for S. caprae) were mined based on pan-genome analysis. Primers targeting molecular target genes showed 100% specificity for 100 non-target reference strains. The detection limit in pure cultures and artificially contaminated food samples was 102 colony-forming unit/mL for S. aureus, S. capitis, S. caprae, and S. epidermidis. Moreover, real-time polymerase chain reaction successfully detected strains isolated from various food matrices. Thus, our method allows an accurate and rapid monitoring of Staphylococcus species and may help control staphylococcal contamination of food.

RevDate: 2021-11-27

Peng S, Petersen JL, Bellone RR, et al (2021)

Decoding the Equine Genome: Lessons from ENCODE.

Genes, 12(11): pii:genes12111707.

The horse reference genome assemblies, EquCab2.0 and EquCab3.0, have enabled great advancements in the equine genomics field, from tools to novel discoveries. However, significant gaps of knowledge regarding genome function remain, hindering the study of complex traits in horses. In an effort to address these gaps and with inspiration from the Encyclopedia of DNA Elements (ENCODE) project, the equine Functional Annotation of Animal Genome (FAANG) initiative was proposed to bridge the gap between genome and gene expression, providing further insights into functional regulation within the horse genome. Three years after launching the initiative, the equine FAANG group has generated data from more than 400 experiments using over 50 tissues, targeting a variety of regulatory features of the equine genome. In this review, we examine how valuable lessons learned from the ENCODE project informed our decisions in the equine FAANG project. We report the current state of the equine FAANG project and discuss how FAANG can serve as a template for future expansion of functional annotation in the equine genome and be used as a reference for studies of complex traits in horse. A well-annotated reference functional atlas will also help advance equine genetics in the pan-genome and precision medicine era.

RevDate: 2021-11-25

Barber AE, Sae-Ong T, Kang K, et al (2021)

Aspergillus fumigatus pan-genome analysis identifies genetic variants associated with human infection.

Nature microbiology, 6(12):1526-1536.

Aspergillus fumigatus is an environmental saprobe and opportunistic human fungal pathogen. Despite an estimated annual occurrence of more than 300,000 cases of invasive disease worldwide, a comprehensive survey of the genomic diversity present in A. fumigatus-including the relationship between clinical and environmental isolates and how this genetic diversity contributes to virulence and antifungal drug resistance-has been lacking. In this study we define the pan-genome of A. fumigatus using a collection of 300 globally sampled genomes (83 clinical and 217 environmental isolates). We found that 7,563 of the 10,907 unique orthogroups (69%) are core and present in all isolates and the remaining 3,344 show presence/absence of variation, representing 16-22% of the genome of each isolate. Using this large genomic dataset of environmental and clinical samples, we found an enrichment for clinical isolates in a genetic cluster whose genomes also contain more accessory genes, including genes coding for transmembrane transporters and proteins with iron-binding activity, and genes involved in both carbohydrate and amino-acid metabolism. Finally, we leverage the power of genome-wide association studies to identify genomic variation associated with clinical isolates and triazole resistance as well as characterize genetic variation in known virulence factors. This characterization of the genomic diversity of A. fumigatus allows us to move away from a single reference genome that does not necessarily represent the species as a whole and better understand its pathogenic versatility, ultimately leading to better management of these infections.

RevDate: 2021-11-24

Almeida OGG, Gimenez MP, ECP De Martinis (2021)

Comparative pangenomic analyses and biotechnological potential of cocoa-related Acetobacter senegalensis strains.

Antonie van Leeuwenhoek [Epub ahead of print].

Acetobacter senegalensis belongs to the group of acetic acid bacteria (AAB) that present potential biotechnological applications, for production of D-gluconate, cellulose and acetic acid. AAB can overcome heat and acid stresses by using strategies involving the overexpression of heat-shock proteins and enzymes from the complex pyrroquinoline-ADH, besides alcohol dehydrogenases (ADH). Nonetheless, the isolation of A. senegalensis and other AAB from food may be challenging due to presence of viable but non-culturable (VBNC) cells and due to uncertainties about nutritional requirements. To contribute for a better understanding of the ecology of AAB, this paper reports on the pangenome analysis of five strains of A. senegalensis recently isolated from a Brazilian spontaneous cocoa fermentation. The results showed biosynthetic clusters exclusively found in some cocoa-related AAB, such as those related to terpene pathways, which are important for flavour development. Genes related to oxidative stress were conserved in all the genomes, with multiple clusters. Moreover, there were genes coding for ADH and putative ABC transporters distributed in core, shell and cloud genomes, while chaperonin-encoding genes were present only in the core and soft-core genomes. Regarding quorum sensing, a response regulator gene was in the shell genome, and the gene encoding for acyl-homoserine lactone efflux protein was in the soft-core genome. There were quorum quenching-related genes, mainly encoding for lactonases, but also for acylases. Moreover, A. senegalensis did not have determinants of virulence or antibiotic resistance, which are good traits for strains intended to be applied in food fermentation.

RevDate: 2021-11-24

Xiao Y, Jiang R, Wu X, et al (2021)

Comparative Genomic Analysis of Stenotrophomonas maltophilia Strain W18 Reveals Its Adaptative Genomic Features for Degrading Polycyclic Aromatic Hydrocarbons.

Microbiology spectrum [Epub ahead of print].

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants that are ubiquitous in the environment. Numerous bacteria have evolved to have degrading genes or pathways to degrade PAHs. Stenotrophomonas maltophilia strain W18 was found to be able to degrade PAHs. Including 43 other complete genome sequences of S. maltophilia strains, we performed a comparative genomic analysis of 44 S. maltophilia strains by running OrthoFinder. A KEGG pathway enrichment analysis of environmental and clinical isolates of S. maltophilia revealed that environmental isolates tended to enhance gene functions such as "energy metabolism," "amino acid metabolism," "xenobiotic biodegradation and metabolism," and "folding, sorting, and degradation." The pangenome of the 44 S. maltophilia strains was open, while the core genome was estimated to reach a steady plateau. Based on gene annotations, we inferred that most of the degradation potential came from the core genome of S. maltophilia, while character genes and accessory genes also contributed to the degradation ability of S. maltophilia W18. The genes expression level of core genes, character genes and accessory genes were proved by RT-qPCR experiment, and accessory genes encoding alcohol dehydrogenase were upregulated most compared with genes with similar functions. We performed a credible comparative genomic analysis of S. maltophilia strains. S. maltophilia W18 was set as a model PAH-degrading bacterium of this species in this study, which would provide guidance for understanding and predicting the degradation mechanisms of other PAH-degrading S. maltophilia strains lacking complete genome data or waiting to be determined. IMPORTANCE This study provided the latest comparative genomic analysis on Stenotrophomonas maltophilia strains and focused on analyzing their genomic features that allow them to adapt to natural environments. In this study, we set S. maltophilia W18 as a typical PAH-degrading strain of this species. By discussing the genomic adaptative features of degrading PAH, we can predict genomic adaptative features of other S. maltophilia PAH-degrading strains since the core function of this species is stable. The gene functions of how S. maltophilia environmental isolates are enhanced for adaptation to various natural environments compared with clinical isolates have been revealed. Combined with a pangenome analysis and RT-qPCR results, we have proved that core genes, character genes, and accessory genes are all involved in PAH degradation. Accessory genes encoding alcohol dehydrogenase were upregulated most compared with core and character genes with similar functions, which suggests that PAH metabolization potential might be enhanced by horizontal gene transfer.

RevDate: 2021-11-24

Bian PP, Zhang Y, Y Jiang (2021)

Pan-genome: setting a new standard for high-quality reference genomes.

Yi chuan = Hereditas, 43(11):1023-1037.

With the release of high-quality reference genomes assembled by long reads from the third-generation sequencing technology, as well as extensive re-sequencing and population genetic analysis, researchers found that a single reference genome does not represent the diversity within a species. The missing sequences on the reference genome result in an incomplete population genetic polymorphism map. The emergence of pan-genome can well repair the deficiency of single reference genome, which include core genome (responsible for basic biological functions and the main phenotypic characteristics within a species) and the variable genome (related to the genetic diversity or biological characteristics). According to the core and variable genome proportion, the types of pan-genomes can be either open or closed. Here, we review the current exploring of pan-genome for a range of species, to discuss the characteristics of pan-genome in various biological groups. The pan-genome of mammals are more likely closed, while the pan-genomes of microbes, angiosperms, and some invertebrates are likely non-closed. It is possible to complete the reference genome and obtain complete variation information through the pan-genomic study, which will contribute to the study of molecular mechanism for genetic diversity and phenotypic evolution.

RevDate: 2021-11-22

Cobian N, Garlet A, Hidalgo-Cantabrana C, et al (2021)

Comparative Genomic Analyses and CRISPR-Cas Characterization of Cutibacterium acnes Provide Insights Into Genetic Diversity and Typing Applications.

Frontiers in microbiology, 12:758749.

Cutibacterium acnes is an important member of the human skin microbiome and plays a critical role in skin health and disease. C. acnes encompasses different phylotypes that have been found to be associated with different skin phenotypes, suggesting a genetic basis for their impact on skin health. Here, we present a comprehensive comparative analysis of 255 C. acnes genomes to provide insights into the species genetic diversity and identify unique features that define various phylotypes. Results revealed a relatively small and open pan genome (6,240 genes) with a large core genome (1,194 genes), and three distinct phylogenetic clades, with multiple robust sub-clades. Furthermore, we identified several unique gene families driving differences between distinct C. acnes clades. Carbohydrate transporters, stress response mechanisms and potential virulence factors, potentially involved in competitive growth and host colonization, were detected in type I strains, which are presumably responsible for acne. Diverse type I-E CRISPR-Cas systems and prophage sequences were detected in select clades, providing insights into strain divergence and adaptive differentiation. Collectively, these results enable to elucidate the fundamental differences among C. acnes phylotypes, characterize genetic elements that potentially contribute to type I-associated dominance and disease, and other key factors that drive the differentiation among clades and sub-clades. These results enable the use of comparative genomics analyses as a robust method to differentiate among the C. acnes genotypes present in the skin microbiome, opening new avenues for the development of biotherapeutics to manipulate the skin microbiota.

RevDate: 2021-11-22

Jiang ZM, Zhang BH, Sun HM, et al (2021)

Properties of Modestobacter deserti sp. nov., a Kind of Novel Phosphate-Solubilizing Actinobacteria Inhabited in the Desert Biological Soil Crusts.

Frontiers in microbiology, 12:742798.

Three Gram-stain-positive, aerobic, motile actinobacterial strains designated as CPCC 205119T, CPCC 205215, and CPCC 205251 were isolated from different biological soil crust samples collected from Tengger Desert, China. The 16S rRNA gene sequence comparison of these three strains showed they had almost identical 16S rRNA genes, which were closely related to members of the family Geodermatophilaceae, with the highest similarities of 96.3-97.3% to the species of Modestobacter. In the phylogenetic tree based on 16S rRNA gene sequences, these isolates clustered into a subclade next to the branch containing the species of Modestobacter lapidis and Modestobacter multiseptatus, within the lineage of the genus Modestobacter. The comparative genomic characteristics (values of ANI, dDDH, AAI, and POCP) and the phenotypic properties (morphological, physiological, and chemotaxonomic characteristics) of these isolates readily supported to affiliate them to the genus Modestobacter as a single separate species. For which, we proposed that the isolates CPCC 205119T, CPCC 205215, and CPCC 205251 represent a novel species of the genus Modestobacter as Modestobacter deserti sp. nov. CPCC 205119T (=I12A-02624=NBRC 113528T=KCTC 49201T) is the type strain. The genome of strain CPCC 205119T consisted of one chromosome (4,843,235bp) containing 4,424 coding genes, 48 tRNA genes, five rRNA genes, three other ncRNA genes, and 101 pseudogenes, with G+C content of 74.7%. The whole-genome sequences analysis indicated that this species contained alkaline phosphatase genes (phoA/phoD), phosphate transport-related genes (phoU, phnC, phnD, phnE, phoB, phoH, phoP, phoR, pitH, ppk, pstA, pstB, pstC, and pstS), trehalose-phosphate synthase gene (otsA), trehalose 6-phosphate phosphatase gene (otsB) and other encoding genes for the properties that help the microorganisms to adapt to harsh environmental conditions prevalent in deserts. Strains of this species could solubilize tricalcium phosphate [Ca3(PO4)2] and phytin, assimilate pyrophosphate, thiophosphate, dithiophosphate, phosphoenol pyruvate, 2-deoxy-d-glucose-6-phosphate, and cysteamine-S-phosphate.

RevDate: 2021-11-21

Pan Y, Zeng Z, Niu H, et al (2021)

Whole-genome epidemiology and characterization of mcr-1-encoding Escherichia coli in aquatic bird farms from the Pearl River Delta, China during 2019-2020.

International journal of antimicrobial agents pii:S0924-8579(21)01313-3 [Epub ahead of print].

Due to their unique breeding pattern, aquatic bird farms are gradually considered as a hotspot in the development and spread of antibiotic resistance. However, the number of comprehensive studies addressing the whole-genomic features of colistin resistant bacteria in aquatic bird farms is currently low. Over a period of two years, we conducted surveillance to determine the whole-genome epidemiology and characterization of mcr-1-positive E. coli in aquatic bird farms in southeastern coastal China. A total of 100 mcr-1-producing isolates in 654 E. coli strains were recovered from 781 samples collected in 11 aquatic bird farms and 1 veterinary clinic in the Pearl River Delta area. Higher resistance phenotypes to 17 antibiotics were found in mcr-1 positive isolates than in other isolates. Then, 20 mcr-1-carrying isolates were sequenced to analyse the whole-genomic features. The molecular typing and antibiotic resistance genes (ARGs)/ virulence factors (VFs) profiles of the isolates showed considerable diversity. Three types of genetic backbones of mcr-1 in the isolates were clustered, and identified in diverse broad host range plasmids and bacterial species. The pan-genome analyses revealed a large genetic pool composed of the isolates. Furthermore, phylogenetic trees of both the isolates in this study and a global dataset were built, indicating the spread of the three mcr-1 backbones and the mcr-1 positive isolates among different habitats, farms, and even countries. This study highlighted that aquatic bird farms may act as an important reservoir for mcr-1-producing E. coli, in which colistin resistance may be spread to diverse habitats, different geographical locations, and even across bacterial species.

RevDate: 2021-11-19

Ferrer L, García-Fonticoba R, Pérez D, et al (2021)

Whole genome sequencing and de novo assembly of Staphylococcus pseudintermedius: a pangenome approach to unravelling pathogenesis of canine pyoderma.

Veterinary dermatology, 32(6):654-663.

BACKGROUND: Staphylococcus pseudintermedius is the main aetiological agent of canine pyoderma. Whole genome sequencing is the most comprehensive way of obtaining relevant genomic information about micro-organisms.

HYPOTHESIS/OBJECTIVES: Oxford Nanopore technology enables quality sequencing and de novo assembly of the whole genome of S. pseudintermedius. Whole genome analysis of S. pseudintermedius may help to better understand the pathogenesis of canine pyodermas.

METHODS AND MATERIALS: Twenty-two strains of S. pseudintermedius isolated from the skin of five healthy dogs and 33 strains isolated from skin of 33 dogs with pyoderma were analysed. DNA was extracted and sequenced using Oxford Nanopore MinION, a new technology that delivers longer reads in a hand-held device. The pangenome was analysed and visualised with Anvi'o 6.1.

RESULTS: Nanopore technology allowed the sequencing and de novo assembly of the genomes of 55 S. pseudintermedius strains isolated from healthy dogs and from dogs with pyoderma. The average genome size of S. pseudintermedius was 2.62 Mbp, with 48% being core genome. Pyoderma isolates contained a higher number of antimicrobial resistance genes, yet the total number of virulence factors genes did not change between isolates from healthy dogs and from dogs with pyoderma. Genomes of meticillin-resistant S. pseudintermedius (MRSP) strains were larger than those of meticillin-susceptible (MSSP) strains (2.80 Mbp versus 2.59 Mbp), as a consequence of a greater presence of antimicrobial resistance genes, phages and prophages.

This technique allows much more precise and easier characterisation of canine S. pseudintermedius populations and may lead to a better understanding of the pathogenesis of canine pyodermas.

RevDate: 2021-11-18

Watson AK, Lopez P, E Bapteste (2021)

Hundreds of out-of-frame remodelled gene families in the E. coli pangenome.

Molecular biology and evolution pii:6430988 [Epub ahead of print].

All genomes include gene families with very limited taxonomic distributions that potentially represent new genes and innovations in protein-coding sequence, raising questions on the origins of such genes. Some of these genes are hypothesised to have formed de novo, from non-coding sequences, and recent work has begun to elucidate the processes by which de novo gene formation can occur. A special case of de novo gene formation, overprinting, describes the origin of new genes from non-coding alternative reading frames of existing open reading frames (ORFs). We argue that additionally, out-of-frame gene fission/fusion events of alternative reading frames of ORFs and out-of-frame lateral gene transfers could contribute to the origin of new gene families. To demonstrate this, we developed an original pattern-search in sequence similarity networks, enhancing the use of these graphs, commonly used to detect in-frame remodelled genes. We applied this approach to gene families in 524 complete genomes of Escherichia coli. We identified 767 gene families whose evolutionary history likely included at least one out-of-frame remodelling event. These genes with out-of-frame components represent ∼2.5% of all genes in the E. coli pangenome, suggesting that alternative reading frames of existing ORFs can contribute to a significant proportion of de novo genes in bacteria.

RevDate: 2021-11-18

Pacheco-Moreno A, Stefanato FL, Ford JJ, et al (2021)

Pan-genome analysis identifies intersecting roles for Pseudomonas specialized metabolites in potato pathogen inhibition.

eLife, 10: pii:71900 [Epub ahead of print].

Agricultural soil harbors a diverse microbiome that can form beneficial relationships with plants, including the inhibition of plant pathogens. Pseudomonas spp. are one of the most abundant bacterial genera in the soil and rhizosphere and play important roles in promoting plant health. However, the genetic determinants of this beneficial activity are only partially understood. Here, we genetically and phenotypically characterize the Pseudomonas fluorescens population in a commercial potato field, where we identify strong correlations between specialized metabolite biosynthesis and antagonism of the potato pathogens Streptomyces scabies and Phytophthora infestans. Genetic and chemical analyses identified hydrogen cyanide and cyclic lipopeptides as key specialized metabolites associated with S. scabies inhibition, which was supported by in planta biocontrol experiments. We show that a single potato field contains a hugely diverse and dynamic population of Pseudomonas bacteria, whose capacity to produce specialized metabolites is shaped both by plant colonization and defined environmental inputs.

RevDate: 2021-11-18

Yates AD, Allen J, Amode RM, et al (2021)

Ensembl Genomes 2022: an expanding genome resource for non-vertebrates.

Nucleic acids research pii:6427344 [Epub ahead of print].

Ensembl Genomes (https://www.ensemblgenomes.org) provides access to non-vertebrate genomes and analysis complementing vertebrate resources developed by the Ensembl project (https://www.ensembl.org). The two resources collectively present genome annotation through a consistent set of interfaces spanning the tree of life presenting genome sequence, annotation, variation, transcriptomic data and comparative analysis. Here, we present our largest increase in plant, metazoan and fungal genomes since the project's inception creating one of the world's most comprehensive genomic resources and describe our efforts to reduce genome redundancy in our Bacteria portal. We detail our new efforts in gene annotation, our emerging support for pangenome analysis, our efforts to accelerate data dissemination through the Ensembl Rapid Release resource and our new AlphaFold visualization. Finally, we present details of our future plans including updates on our integration with Ensembl, and how we plan to improve our support for the microbial research community. Software and data are made available without restriction via our website, online tools platform and programmatic interfaces (available under an Apache 2.0 license). Data updates are synchronised with Ensembl's release cycle.

RevDate: 2021-11-16

Lu Y, Wang J, Chen B, et al (2021)

A donor-DNA-free CRISPR/Cas-based approach to gene knock-up in rice.

Nature plants, 7(11):1445-1452.

Structural variations (SVs), such as inversion and duplication, contribute to important agronomic traits in crops1. Pan-genome studies revealed that SVs were a crucial and ubiquitous force driving genetic diversification2-4. Although genome editing can effectively create SVs in plants and animals5-8, the potential of designed SVs in breeding has been overlooked. Here, we show that new genes and traits can be created in rice by designed large-scale genomic inversion or duplication using CRISPR/Cas9. A 911 kb inversion on chromosome 1 resulted in a designed promoter swap between CP12 and PPO1, and a 338 kb duplication between HPPD and Ubiquitin2 on chromosome 2 created a novel gene cassette at the joint, promoterUbiquitin2::HPPD. Since the original CP12 and Ubiquitin2 genes were highly expressed in leaves, the expression of PPO1 and HPPD in edited plants with homozygous SV alleles was increased by tens of folds and conferred sufficient herbicide resistance in field trials without adverse effects on other important agronomic traits. CRISPR/Cas-based genome editing for gene knock-ups has been generally considered very difficult without inserting donor DNA as regulatory elements. Our study challenges this notion by providing a donor-DNA-free strategy, thus greatly expanding the utility of CRISPR/Cas in plant and animal improvements.

RevDate: 2021-11-15

Bach E, Sant'Anna FH, Dos Santos Seger GD, et al (2021)

Pangenome inventory of Burkholderia sensu lato, Burkholderia sensu stricto, and the Burkholderia cepacia complex reveals the uniqueness of Burkholderia catarinensis.

Genomics pii:S0888-7543(21)00393-1 [Epub ahead of print].

Here the pangenome analysis of Burkholderia sensu lato (s.l.) was performed for the first time, together with an updated analysis of the pangenome of Burkholderia sensu stricto, and Burkholderia cepacia complex (Bcc) focusing on the Bcc B. catarinensis specific features of its re-sequenced genome. The pangenome of Burkholderia s.l., Burkholderia s.s., and of the Bcc are open, composed of more than 96% of accessory genes, and more than 62% of unknown genes. Functional annotations showed that secondary metabolism genes belong to the variable portion of genomes, which might explain their production of several compounds with varied bioactivities. Taken together, this work shows the great variability and uniqueness of these genomes and reveals an underexplored unknown potential in poorly characterized genes. Regarding B. catarinensis 89T, its genome harbors genes related to hydrolases production and plant growth promotion. This draft genome will be valuable for further investigation of its biotechnological potentials.

RevDate: 2021-11-15

Jha V, Purohit H, NA Dafale (2021)

Revealing the potential of Klebsiella pneumoniae PVN-1 for plant beneficial attributes by genome sequencing and analysis.

3 Biotech, 11(11):473.

Genome sequencing of Klebsiella pneumoniae PVN-1, isolated from effluent treatment plant (ETP), generates a 5.064 Mb draft genome with 57.6% GC content. The draft genome assembled into 19 contigs comprises 4783 proteins, 3 rRNA, 44 tRNA, 8 other RNA, 4911 genes, and 73 pseudogenes. Genome information revealed the presence of phosphate metabolism/solubilizing, potassium solubilizing, auxin production, and other plant benefiting attributes like enterobactin and pyrroloquinoline quinone biosynthesis genes. Presence of gcd and pqq genes in K. pneumoniae PVN-1 genome validates the inorganic phosphate solubilizing potential (528.5 mg/L). Pangenome analysis identified a unique 5'-Nucleotidase that further assists in enhanced phosphate acquisition. Additionally, the genetic potential for complete benzoate, catechol, and phenylacetate degradation with stress response and heavy metal (Cu, Zn, Ni, Co) resistance was identified in K. pneumoniae PVN-1. Functioning of annotated plant benefiting genes validates by the metabolic activity of auxin production (7.40 µg/mL), nitrogen fixation, catalase activity, potassium solubilization (solubilization index-3.47), and protease activity (proteolytic index-2.27). In conclusion, the K. pneumoniae PVN-1 genome has numerous beneficial qualities that can be employed to enhance plant growth as well as for phytoremediation.

Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-021-03020-2.

RevDate: 2021-11-13

Cheng X, Yang B, Zheng J, et al (2021)

Cadmium stress triggers significant metabolic reprogramming in Enterococcus faecium CX 2-6.

Computational and structural biotechnology journal, 19:5678-5687.

Heavy metal pollutions in the soils are increasingly threatening the global crop and food production. Using plant associated bacteria to remediate heavy metal contamination is a promising approach. We have isolated a cadmium (Cd) resistant Enterococcus faecium strain CX 2-6 from a heavy metal contaminated farmland. We have shown that: (i) CX 2-6 can tolerate cadmium (Cd) with a slower growth rate; (ii) The CX 2-6 complete genome is fully assembled using PacBio long reads; (iii) Differential expression analysis found 47% of CX 2-6 genes are significantly affected by Cd treatment and form three gene groups with distinct expression profiles; (iv) Differentially expressed genes (DEGs) form physically linked gene clusters in the CX 2-6 genome, and one of the gene clusters corresponds to a prophage that is unique to CX 2-6 and is strongly activated when Cd concentration is higher; (v) A majority of DEGs responding to Cd treatment are present in the core genome; and (vi) 55 noncoding RNA genes are identified and 49 of them are DEGs responding to cadmium stress. Our pan-genome analysis and comparative RNA-seq data analysis has significantly improved our understanding of the metabolic reprogramming of E. faecium CX 2-6 under Cd stress.

RevDate: 2021-11-11

Urhan A, T Abeel (2021)

A comparative study of pan-genome methods for microbial organisms: Acinetobacter baumannii pan-genome reveals structural variation in antimicrobial resistance-carrying plasmids.

Microbial genomics, 7(11):.

Microbial organisms have diverse populations, where using a single linear reference sequence in comparative studies introduces reference-bias in downstream analyses, and leads to a failure to account for variability in the population. Recently, pan-genome graphs have emerged as an alternative to the traditional linear reference with many successful applications and a rapid increase in the number of methods available in the literature. Despite this enthusiasm, there has been no attempt at exploring these graph construction methods in depth, demonstrating their practical use. In this study, we aim to develop a general guide to help researchers who may want to incorporate pan-genomes in their analyses of microbial organisms. We evaluated the state-of-the art pan-genome construction tools to model a collection of 70 Acinetobacter baumannii strains. Our results suggest that all tools produced pan-genome graphs conforming to our expectations based on previous literature, and that their approach to homologue detection is likely to be the most influential in determining the final size and complexity of the pan-genome. The graphs overlapped most in the core pan-genome content while the cloud genes varied significantly among tools. We propose an alternative approach for pan-genome construction by combining two of the tools, Panaroo and Ptolemy, to further exploit them in downstream analyses, and demonstrate the effectiveness of our pipeline for structural variant calling in beta-lactam resistance genes in the same set of A. baumannii isolates, identifying various transposon structures for carbapenem resistance in chromosome, as well as plasmids. We identify a novel plasmid structure in two multidrug-resistant clinical isolates that had previously been studied, and which could be important for their resistance phenotypes.

RevDate: 2021-11-12

Varshney RK, Roorkiwal M, Sun S, et al (2021)

A chickpea genetic variation map based on the sequencing of 3,366 genomes.

Nature [Epub ahead of print].

Zero hunger and good health could be realized by 2030 through effective conservation, characterization and utilization of germplasm resources1. So far, few chickpea (Cicer arietinum) germplasm accessions have been characterized at the genome sequence level2. Here we present a detailed map of variation in 3,171 cultivated and 195 wild accessions to provide publicly available resources for chickpea genomics research and breeding. We constructed a chickpea pan-genome to describe genomic diversity across cultivated chickpea and its wild progenitor accessions. A divergence tree using genes present in around 80% of individuals in one species allowed us to estimate the divergence of Cicer over the last 21 million years. Our analysis found chromosomal segments and genes that show signatures of selection during domestication, migration and improvement. The chromosomal locations of deleterious mutations responsible for limited genetic diversity and decreased fitness were identified in elite germplasm. We identified superior haplotypes for improvement-related traits in landraces that can be introgressed into elite breeding lines through haplotype-based breeding, and found targets for purging deleterious alleles through genomics-assisted breeding and/or gene editing. Finally, we propose three crop breeding strategies based on genomic prediction to enhance crop productivity for 16 traits while avoiding the erosion of genetic diversity through optimal contribution selection (OCS)-based pre-breeding. The predicted performance for 100-seed weight, an important yield-related trait, increased by up to 23% and 12% with OCS- and haplotype-based genomic approaches, respectively.

RevDate: 2021-11-12
CmpDate: 2021-11-12

Her HL, Lin PT, YW Wu (2021)

PangenomeNet: a pan-genome-based network reveals functional modules on antimicrobial resistome for Escherichia coli strains.

BMC bioinformatics, 22(1):548.

BACKGROUND: Discerning genes crucial to antimicrobial resistance (AMR) mechanisms is becoming more and more important to accurately and swiftly identify AMR pathogenic strains. Pangenome-wide association studies (e.g. Scoary) identified numerous putative AMR genes. However, only a tiny proportion of the putative resistance genes are annotated by AMR databases or Gene Ontology. In addition, many putative resistance genes are of unknown function (termed hypothetical proteins). An annotation tool is crucially needed in order to reveal the functional organization of the resistome and expand our knowledge of the AMR gene repertoire.

RESULTS: We developed an approach (PangenomeNet) for building co-functional networks from pan-genomes to infer functions for hypothetical genes. Using Escherichia coli as an example, we demonstrated that it is possible to build co-functional network from its pan-genome using co-inheritance, domain-sharing, and protein-protein-interaction information. The investigation of the network revealed that it fits the characteristics of biological networks and can be used for functional inferences. The subgraph consisting of putative meropenem resistance genes consists of clusters of stress response genes and resistance gene acquisition pathways. Resistome subgraphs also demonstrate drug-specific AMR genes such as beta-lactamase, as well as functional roles shared among multiple classes of drugs, mostly in the stress-related pathways.

CONCLUSIONS: By demonstrating the idea of pan-genome-based co-functional network on the E. coli species, we showed that the network can infer functional roles of the genes, including those without functional annotations, and provides holistic views on the putative antimicrobial resistomes. We hope that the pan-genome network idea can help formulate hypothesis for targeted experimental works.

RevDate: 2021-11-08

Yildirir G, Sperschneider J, Malar C M, et al (2021)

Long reads and Hi-C sequencing illuminate the two compartment genome of the model arbuscular mycorrhizal symbiont Rhizophagus irregularis.

The New phytologist [Epub ahead of print].

Chromosome folding links genome structure with gene function by generating distinct nuclear compartments and topologically associating domains (TADs). In mammals, these undergo preferential interactions and regulate gene expression. However, their role in fungal genome biology is unclear. Here, we combine Nanopore (ONT) sequencing with chromatin conformation capture sequencing (Hi-C) to reveal chromosome and epigenetic diversity in a group of obligate plant symbionts; the arbuscular mycorrhizal fungi (AMF). We find that five phylogenetically distinct strains of the model AMF Rhizophagus irregularis carry 33 chromosomes with substantial within species variability in size, as well as in gene and repeat content. Strain-specific Hi-C contact maps reveal a 'checkerboard' pattern that underline two dominant euchromatin (A) and heterochromatin (B) compartments. Each compartment differs in the level of gene transcription, regulation of candidate effectors and methylation frequencies. The A-compartment is more gene-dense and contains most core genes, while the B-compartment is more repeat-rich and has higher rates of chromosomal rearrangement. While the B-compartment is transcriptionally repressed, it has significantly more secreted proteins and in planta up-regulated candidate effectors, suggesting a possible host-induced change in chromosome conformation. Overall, this study provides a fine-scale view into the genome biology and evolution of model plant symbionts, and opens avenues to study the epigenetic mechanisms that modify chromosome folding during host-microbe interactions.

RevDate: 2021-11-08

Ravin NV, Rudenko TS, Smolyakov DD, et al (2021)

Comparative Genome Analysis of the Genus Thiothrix Involving Three Novel Species, Thiothrix subterranea sp. nov. Ku-5, Thiothrix litoralis sp. nov. AS and "Candidatus Thiothrix anitrata" sp. nov. A52, Revealed the Conservation of the Pathways of Dissimilatory Sulfur Metabolism and Variations in the Genetic Inventory for Nitrogen Metabolism and Autotrophic Carbon Fixation.

Frontiers in microbiology, 12:760289.

Two strains of filamentous, colorless sulfur bacteria were isolated from bacterial fouling in the outflow of hydrogen sulfide-containing waters from a coal mine (Thiothrix sp. Ku-5) and on the seashore of the White Sea (Thiothrix sp. AS). Metagenome-assembled genome (MAG) A52 was obtained from a sulfidic spring in the Volgograd region, Russia. Phylogenetic analysis based on the 16S rRNA gene sequences showed that all genomes represented the genus Thiothrix. Based on their average nucleotide identity and digital DNA-DNA hybridization data these new isolates and the MAG represent three species within the genus Thiothrix with the proposed names Thiothrix subterranea sp. nov. Ku-5T, Thiothrix litoralis sp. nov. AST, and "Candidatus Thiothrix anitrata" sp. nov. A52. The complete genome sequences of Thiothrix fructosivorans QT and Thiothrix unzii A1T were determined. Complete genomes of seven Thiothrix isolates, as well as two MAGs, were used for pangenome analysis. The Thiothrix core genome consisted of 1,355 genes, including ones for the glycolysis, the tricarboxylic acid cycle, the aerobic respiratory chain, and the Calvin cycle of carbon fixation. Genes for dissimilatory oxidation of reduced sulfur compounds, namely the branched SOX system (SoxAXBYZ), direct (soeABC) and indirect (aprAB, sat) pathways of sulfite oxidation, sulfur oxidation complex Dsr (dsrABEFHCEMKLJONR), sulfide oxidation systems SQR (sqrA, sqrF), and FCSD (fccAB) were found in the core genome. Genomes differ in the set of genes for dissimilatory reduction of nitrogen compounds, nitrogen fixation, and the presence of various types of RuBisCO.

RevDate: 2021-11-05

Cuny H, Offret C, Boukerb AM, et al (2021)

Pseudoalteromonas ostreae sp. nov., a new bacterial species harboured by the flat oyster Ostrea edulis.

International journal of systematic and evolutionary microbiology, 71(11):.

Three bacterial strains, named hOe-66T, hOe-124 and hOe-125, were isolated from the haemolymph of different specimens of the flat oyster Ostrea edulis collected in Concarneau bay (Finistère, France). These strains were characterized by a polyphasic approach, including (i) whole genome analyses with 16S rRNA gene sequence alignment and pangenome analysis, determination of the G+C content, average nucleotide identity (ANI), and in silico DNA-DNA hybridization (isDDH), and (ii) fatty acid methyl ester and other phenotypic analyses. Strains hOe-66T, hOe-124 and hOe-125 were closely related to both type strains Pseudoalteromonas rhizosphaerae RA15T and Pseudoalteromonas neustonica PAMC 28425T with less than 93.3% ANI and 52.3% isDDH values. Regarding their phenotypic traits, the three strains were Gram-negative, 1-2 µm rod-shaped, aerobic, motile and non-spore-forming bacteria. Cells grew optimally at 25 °C in 2.5% NaCl and at 7-8 pH. The most abundant fatty acids were summed feature 3 (C16:1 ω7c/C16:1 ω6c), C16:0 and C17:1 ω8c. The strains carried a genome average size of 4.64 Mb and a G+C content of 40.28 mol%. The genetic and phenotypic results suggested that strains hOe-66T, hOe-124 and hOe-125 belong to a new species of the genus Pseudoalteromonas. In this context, we propose the name Pseudoalteromonas ostreae sp. nov. The type strain is hOe-66T (=CECT 30303T=CIP 111911T).

RevDate: 2021-11-04

Kurilung A, Perreten V, N Prapasarakul (2021)

Comparative Genomic Analysis and a Novel Set of Missense Mutation of the Leptospira weilii Serogroup Mini From the Urine of Asymptomatic Dogs in Thailand.

Frontiers in microbiology, 12:731937.

Leptospira weilii belongs to the pathogenic Leptospira group and is a causal agent of human and animal leptospirosis in many world regions. L. weilii can produce varied clinical presentations from asymptomatic through acute to chronic infections and occupy several ecological niches. Nevertheless, the genomic feature and genetic basis behind the host adaptability of L. weilii remain elusive due to limited information. Therefore, this study aimed to examine the complete circular genomes of two new L. weilii serogroup Mini strains (CUDO6 and CUD13) recovered from the urine of asymptomatic dogs in Thailand and then compared with the 17 genomes available for L. weilii. Variant calling analysis (VCA) was also undertaken to gain potential insight into the missense mutations, focusing on the known pathogenesis-related genes. Whole genome sequences revealed that the CUDO6 and CUD13 strains each contained two chromosomes and one plasmid, with average genome size and G+C content of 4.37 Mbp and 40.7%, respectively. Both strains harbored almost all the confirmed pathogenesis-related genes in Leptospira. Two novel plasmid sequences, pDO6 and pD13, were identified in the strains CUDO6 and CUD13. Both plasmids contained genes responsible for stress response that may play important roles in bacterial adaptation during persistence in the kidneys. The core-single nucleotide polymorphisms phylogeny demonstrated that both strains had a close genetic relationship. Amongst the 19 L. weilii strains analyzed, the pan-genome analysis showed an open pan-genome structure, correlated with their high genetic diversity. VCA identified missense mutations in genes involved in endoflagella, lipopolysaccharide (LPS) structure, mammalian cell entry protein, and hemolytic activities, and may be associated with host-adaptation in the strains. Missense mutations of the endoflagella genes of CUDO6 and CUD13 were associated with loss of motility. These findings extend the knowledge about the pathogenic molecular mechanisms and genomic evolution of this important zoonotic pathogen.

RevDate: 2021-11-02

Song JM, Zhang Y, Zhou ZW, et al (2021)

Oil plant genomes: current state of the science.

Journal of experimental botany pii:6417299 [Epub ahead of print].

Vegetable oils are indispensable nutritional components of human diet as well as important raw materials for a variety of industrial applications such as pharmaceuticals, cosmetics, oleochemicals and biofuels. The oil plant genomes are highly diverse, and the genetic variation leads to the diversity in oil biosynthesis and accumulation along with agronomic traits. This review discusses the plant oil biosynthetic pathways, the current state of genome assembly, the polyploidy and asymmetric evolution genomes of oil plants and their wild relatives, and the research progress of pan-genomics in oil plants. The availability of complete high-resolution genomes and pangenomes has enabled the identification of structural variations in the genomes that are associated with the diversity of agronomic and environment fitness traits. These and more future genomes also provide powerful tools to understand crop evolution and to harvest the rich natural variations to improve oil crops for enhanced productivity, oil quality, and adaptability to changing environments.

RevDate: 2021-10-30

Caicedo-Montoya C, Gómez-Román MP, Vázquez-Hernández M, et al (2021)

Evolutionary genomics and biosynthetic potential of novel environmental Actinobacteria.

Applied microbiology and biotechnology [Epub ahead of print].

Actinobacteria embroil Gram-positive microbes with high guanine and cytosine contents in their DNA. They are the source of most antimicrobials of bacterial origin utilized in medicine today. Their genomes are among the richest in novel secondary metabolites with high biotechnological potential. Actinobacteria reveal complex patterns of evolution, responses, and adaptations to their environment, which are not yet well understood. We analyzed three novel plant isolates and explored their habitat adaptation, evolutionary patterns, and potential secondary metabolite production. The phylogenomically characterized isolates belonged to Actinoplanes sp. TFC3, Streptomyces sp. L06, and Embleya sp. NF3. Positively selected genes, relevant in strain evolution, encoded enzymes for stress resistance in all strains, including porphyrin, chlorophyll, and ubiquinone biosynthesis in Embleya sp. NF3. Streptomyces sp. L06 encoded for pantothenate and proteins for CoA biosynthesis with evidence of positive selection; furthermore, Actinoplanes sp. TFC3 encoded for a c-di-GMP synthetase, with adaptive mutations. Notably, the genomes harbored many genes involved in the biosynthesis of at least ten novel secondary metabolites, with many avenues for future new bioactive compound characterization-specifically, Streptomyces sp. L06 could make new ribosomally synthesized and post-translationally modified peptides, while Embleya sp. NF3 could produce new non-ribosomal peptide synthetases and ribosomally synthesized and post-translationally modified peptides. At the same time, TFC3 has particularly enriched in terpene and polyketide synthases. All the strains harbored conserved genes in response to diverse environmental stresses, plant growth promotion factors, and degradation of various carbohydrates, which supported their endophytic lifestyle and showed their capacity to colonize other niches. This study aims to provide a comprehensive estimation of the genomic features of novel Actinobacteria. It sets the groundwork for future research into experimental tests with new bioactive metabolites with potential application in medicine, biofertilizers, and plant biomass residue utilization, with potential application in medicine, as biofertilizers and in plant biomass residues utilization. KEY POINTS: • Potential of novel environmental bacteria for secondary metabolites production • Exploring the genomes of three novel endophytes isolated from a medicinal tree • Pan-genome analysis of Actinobacteria genera.

RevDate: 2021-10-29

Rodrigues GL, Matteoli FP, Gazara RK, et al (2021)

Characterization of cellular, biochemical and genomic features of the diazotrophic plant growth-promoting bacterium Azospirillum sp. UENF-412522, a novel member of the Azospirillum genus.

Microbiological research, 254:126896 pii:S0944-5013(21)00202-0 [Epub ahead of print].

Given their remarkable beneficial effects on plant growth, several Azospirillum isolates currently integrate the formulations of various commercial inoculants. Our research group isolated a new strain, Azospirillum sp. UENF-412522, from passion fruit rhizoplane. This isolate uses carbon sources that are partially distinct from closely-related Azospirillum isolates. Scanning electron microscopy analysis and population counts demonstrate the ability of Azospirillum sp. UENF-412522 to colonize the surface of passion fruit roots. In vitro assays demonstrate the ability of Azospirillum sp. UENF-412522 to fix atmospheric nitrogen, to solubilize phosphate and to produce indole-acetic acid. Passion fruit plantlets inoculated with Azospirillum sp. UENF-41255 showed increased shoot and root fresh matter by 13,8% and 88,6% respectively, as well as root dry matter by 61,4%, further highlighting its biotechnological potential for agriculture. We sequenced the genome of Azospirillum sp. UENF-412522 to investigate the genetic basis of its plant-growth promotion properties. We identified the key nif genes for nitrogen fixation, the complete PQQ operon for phosphate solubilization, the acdS gene that alleviates ethylene effects on plant growth, and the napCAB operon, which produces nitrite under anoxic conditions. We also found several genes conferring resistance to common soil antibiotics, which are critical for Azospirillum sp. UENF-412522 survival in the rhizosphere. Finally, we also assessed the Azospirillum pangenome and highlighted key genes involved in plant growth promotion. A phylogenetic reconstruction of the genus was also conducted. Our results support Azospirillum sp. UENF-412522 as a good candidate for bioinoculant formulations focused on plant growth promotion in sustainable systems.

RevDate: 2021-10-29

Huang YS, Lin CY, WC Cheng (2021)

Investigating the Transcriptomic and Expression Presence-Absence Variation Exist in Japanese Eel (Anguilla japonica), a Primitive Teleost.

Marine biotechnology (New York, N.Y.) [Epub ahead of print].

The pan-genome was defined as the complete gene set across strains, and it is built upon genes displaying presence-absence variations (PAVs); the pan-transcriptome is defined by recalling the pan-genome. Indeed, a PAV is reflected from the expression presence-absence variation (ePAV). In this study, treated with androgen, eels, which are a primitive fish from the basal lineage of Teleost, with different ovarian developments were chosen and submitted to RAN-sequencing. Transcriptomes were the assembly against eel genome scaffolds; a pair was the unit (the same eel before and after treatment) to analyze DEGs (differentially expressed genes); the core, unique, or accessory genes were identified, and the list of DEGs was analyzed to investigate ePAV. The results suggest that there was ePAV in Japanese eel, and the ePAV of eel was analyzed by pathway enrichment. These results signify the importance of genetic differential expression on the variations of phenotypes by androgen, and a transcriptomic approach appears to enable extracting multiple layers of genomic data.

RevDate: 2021-10-29

Reis AC, MV Cunha (2021)

The open pan-genome architecture and virulence landscape of Mycobacterium bovis.

Microbial genomics, 7(10):.

RevDate: 2021-10-29

Zin NM, Ismail A, Mark DR, et al (2021)

Adaptation to Endophytic Lifestyle Through Genome Reduction by Kitasatospora sp. SUK42.

Frontiers in bioengineering and biotechnology, 9:740722 pii:740722.

Endophytic actinobacteria offer great potential as a source of novel bioactive compounds. In order to investigate the potential for the production of secondary metabolites by endophytes, we recovered a filamentous microorgansism from the tree Antidesma neurocarpum Miq. After phenotypic analysis and whole genome sequencing we demonstrated that this organism, SUK42 was a member of the actinobacterial genus Kitasatospora. This strain has a small genome in comparison with other type strains of this genus and has lost metabolic pathways associated with Stress Response, Nitrogen Metabolism and Secondary Metabolism. Despite this SUK42 can grow well in a laboratory environment and encodes a core genome that is consistent with other members of the genus. Finally, in contrast to other members of Kitasatospora, SUK42 encodes saccharide secondary metabolite biosynthetic gene clusters, one of which with similarity to the acarviostatin cluster, the product of which displays α-amylase inhibitory activity. As extracts of the host plant demonstrate this inhibitory activity, it suggests that the potential medicinal properties of A. neurocarpum Miq might be provided by the endophytic partner and illustrate the potential for exploitation of endophytes for clinical or industrial uses.

RevDate: 2021-10-28

Wu H, Yang ZK, Yang T, et al (2022)

An Effective Preprocessing Method for High-Quality Pan-Genome Analysis of Bacillus subtilis and Escherichia coli.

Methods in molecular biology (Clifton, N.J.), 2377:371-390.

Bacillus subtilis and Escherichia coli, as widely used microbial species, are of great significance in studying microbial community relationships, adaptive evolution in various niches, engineering cell factories that produce specific products, and designing genome reduction. The pan-genome analysis is an effective method for studying the characteristics and functions of genes among and within species. Many research directions and conclusions usually depend on accurate gene identification and reliable pan-genome results. However, there currently lack enough studies showing how to achieve high-quality pan-genome results between or within certain species. This chapter will take Bacillus subtilis as an example to introduce a stepwise manner for improving the quality of the pan-genome by gradually removing confounding strains step-by-step, and ultimately obtaining a reliable high-quality pan-genome landscape of Bacillus subtilis, which could be used as a quality control protocol in pan-genome analysis pipeline. Finally, we suggest further improving the pan-genome analysis results of Escherichia coli to prove the feasibility and credibility of the quality control protocol for obtaining high-quality pan-genome landscape.

RevDate: 2021-10-27

Mullally CA, Mikucki A, Wise MJ, et al (2021)

Modelling evolutionary pathways for commensalism and hypervirulence in Neisseria meningitidis.

Microbial genomics, 7(10):.

Neisseria meningitidis, the meningococcus, resides exclusively in humans and causes invasive meningococcal disease (IMD). The population of N. meningitidis is structured into stable clonal complexes by limited horizontal recombination in this naturally transformable species. N. meningitidis is an opportunistic pathogen, with some clonal complexes, such as cc53, effectively acting as commensal colonizers, while other genetic lineages, such as cc11, are rarely colonizers but are over-represented in IMD and are termed hypervirulent. This study examined theoretical evolutionary pathways for pathogenic and commensal lineages by examining the prevalence of horizontally acquired genomic islands (GIs) and loss-of-function (LOF) mutations. Using a collection of 4850 genomes from the BIGSdb database, we identified 82 GIs in the pan-genome of 11 lineages (10 hypervirulent and one commensal lineage). A new computational tool, Phaser, was used to identify frameshift mutations, which were examined for statistically significant association with genetic lineage. Phaser identified a total of 144 frameshift loci of which 105 were shown to have a statistically significant non-random distribution in phase status. The 82 GIs, but not the LOF loci, were associated with genetic lineage and invasiveness using the disease carriage ratio metric. These observations have been integrated into a new model that infers the early events of the evolution of the human adapted meningococcus. These pathways are enriched for GIs that are involved in modulating attachment to the host, growth rate, iron uptake and toxin expression which are proposed to increase competition within the meningococcal population for the limited environmental niche of the human nasopharynx. We surmise that competition for the host mucosal surface with the nasopharyngeal microbiome has led to the selection of isolates with traits that enable access to cell types (non-phagocytic and phagocytic) in the submucosal tissues leading to an increased risk for IMD.

RevDate: 2021-10-26

Dutra-Silva L, Matteoli FP, ACM Arisi (2021)

Distribution of Genes Related to Probiotic Effects Across Lacticaseibacillus rhamnosus Revealed by Population Structure.

Probiotics and antimicrobial proteins [Epub ahead of print].

The Gram-positive Lacticaseibacillus rhamnosus has been broadly reported as capable of exerting beneficial health effects. Bacterial genomic diversity may promote niche specialization, thus creating subpatterns within populations. As L. rhamnosus advantageous effects have been widely reported at strain level and few is known regarding the distribution of beneficial genes among L. rhamnosus strains, we investigated all publicly available genomes of Lactobacillus and Lacticaseibacillus genera to study the pangenome and general population structure of L. rhamnosus. Core genome multilocus sequence typing detected eight L. rhamnosus phylogroups (PG1 to PG8). L. rhamnosus harbors an open pangenome; PG1, PG3, PG4, and PG5 exhibited highly conserved gene distribution patterns. Genes significantly associated to the PG1, which comprises L. rhamnosus GG, are mainly phage-related. The adhesion operon spaCBA-srtC1 was found in 44 (24.7%) genomes; however, considering only the PG1, the prevalence was of 65%. In PG2 the spaCBA-srtC1 prevalence was of 43%. Nevertheless, both human and milk-derived strains harbored this operon. Further, two main types of bacteriocin clusters were found (Bact1 and Bact2). Bact1 predictions indicate the presence of garQ, encoding the class II bacteriocin garvieacin Q, that is mainly present in the closely related PG8A and a PG2 subcluster. PG2 harbors two distinct subclusters, harboring either spaCBA-srtC1 or Bact1. Our findings provide novel insights on the distribution of biotechnological relevant genes across L. rhamnosus population, uncovering intra-species patterns that may bring forth the development of more efficient probiotic products.

RevDate: 2021-10-26

Qiao Q, Edger PP, Xue L, et al (2021)

Evolutionary history and pan-genome dynamics of strawberry (Fragaria spp.).

Proceedings of the National Academy of Sciences of the United States of America, 118(45):.

Strawberry (Fragaria spp.) has emerged as a model system for various fundamental and applied research in recent years. In total, the genomes of five different species have been sequenced over the past 10 y. Here, we report chromosome-scale reference genomes for five strawberry species, including three newly sequenced species' genomes, and genome resequencing data for 128 additional accessions to estimate the genetic diversity, structure, and demographic history of key Fragaria species. Our analyses obtained fully resolved and strongly supported phylogenies and divergence times for most diploid strawberry species. These analyses also uncovered a new diploid species (Fragaria emeiensis Jia J. Lei). Finally, we constructed a pan-genome for Fragaria and examined the evolutionary dynamics of gene families. Notably, we identified multiple independent single base mutations of the MYB10 gene associated with white pigmented fruit shared by different strawberry species. These reference genomes and datasets, combined with our phylogenetic estimates, should serve as a powerful comparative genomic platform and resource for future studies in strawberry.

RevDate: 2021-10-25

Oshkin IY, Danilova OV, But SY, et al (2021)

Expanding Characterized Diversity and the Pool of Complete Genome Sequences of Methylococcus Species, the Bacteria of High Environmental and Biotechnological Relevance.

Frontiers in microbiology, 12:756830.

The bacterial genus Methylococcus, which comprises aerobic thermotolerant methanotrophic cocci, was described half-a-century ago. Over the years, a member of this genus, Methylococcus capsulatus Bath, has become a major model organism to study genomic and metabolic basis of obligate methanotrophy. High biotechnological potential of fast-growing Methylococcus species, mainly as a promising source of feed protein, has also been recognized. Despite this big research attention, the currently cultured Methylococcus diversity is represented by members of the two species, M. capsulatus and M. geothermalis, while finished genome sequences are available only for two strains of these methanotrophs. This study extends the pool of phenotypically characterized Methylococcus strains with good-quality genome sequences by contributing four novel isolates of these bacteria from activated sludge, landfill cover soil, and freshwater sediments. The determined genome sizes of novel isolates varied between 3.2 and 4.0Mb. As revealed by the phylogenomic analysis, strains IO1, BH, and KN2 affiliate with M. capsulatus, while strain Mc7 may potentially represent a novel species. Highest temperature optima (45-50°C) and highest growth rates in bioreactor cultures (up to 0.3h-1) were recorded for strains obtained from activated sludge. The comparative analysis of all complete genomes of Methylococcus species revealed 4,485 gene clusters. Of these, pan-genome core comprised 2,331 genes (on average 51.9% of each genome), with the accessory genome containing 846 and 1,308 genes in the shell and the cloud, respectively. Independently of the isolation source, all strains of M. capsulatus displayed surprisingly high genome synteny and a striking similarity in gene content. Strain Mc7 from a landfill cover soil differed from other isolates by the high content of mobile genetic elements in the genome and a number of genome-encoded features missing in M. capsulatus, such as sucrose biosynthesis and the ability to scavenge phosphorus and sulfur from the environment.

RevDate: 2021-10-24

Yu C, Wang H, Blaustein RA, et al (2021)

Pangenomic and functional investigations for dormancy and biodegradation features of an organic pollutant-degrading bacterium Rhodococcus biphenylivorans TG9.

The Science of the total environment pii:S0048-9697(21)06219-7 [Epub ahead of print].

Environmental bacteria contain a wealth of untapped potential in the form of biodegradative genes. Leveraging this potential can often be confounded by a lack of understanding of fundamental survival strategies, like dormancy, for environmental stress. Investigating bacterial dormancy-to-degradation relationships enables improvement of bioremediation. Here, we couple genomic and functional assessment to provide context for key attributes of the organic pollutant-degrading strain Rhodococcus biphenylivorans TG9. Whole genome sequencing, pangenome analysis and functional characterization were performed to elucidate important genes and gene products, including antimicrobial resistance, dormancy, and degradation. Rhodococcus as a genus has strong potential for degradation and dormancy, which we demonstrate using R. biphenylivorans TG9 as a model. We identified four Resuscitation-promoting factor (Rpf) encoding genes in TG9 involved in dormancy and resuscitation. We demonstrate that R. biphenylivorans TG9 grows on fourteen typical organic pollutants, and exhibits a robust ability to degrade biphenyl and several congeners of polychlorinated biphenyls. We further induced TG9 into a dormant state and demonstrated pronounced differences in morphology and activity. Together, these results expand our understanding of the genus Rhodococcus and the relationship between dormancy and biodegradation in the presence of environmental stressors.

RevDate: 2021-10-22

Sandholt AKS, Neimanis A, Roos A, et al (2021)

Genomic signatures of host adaptation in group B Salmonella enterica ST416/ST417 from harbour porpoises.

Veterinary research, 52(1):134.

A type of monophasic group B Salmonella enterica with the antigenic formula 4,12:a:- ("Fulica-like") has been described as associated with harbour porpoises (Phocoena phocoena), most frequently recovered from lung samples. In the present study, lung tissue samples from 47 porpoises found along the Swedish coast or as bycatch in fishing nets were analysed, two of which were positive for S. enterica. Pneumonia due to the infection was considered the likely cause of death for one of the two animals. The recovered isolates were whole genome sequenced and found to belong to sequence type (ST) 416 and to be closely related to ST416/ST417 porpoise isolates from UK waters as determined by core-genome MLST. Serovars Bispebjerg, Fulica and Abortusequi were identified as distantly related to the porpoise isolates, but no close relatives from other host species were found. All ST416/417 isolates had extensive loss of function mutations in key Salmonella pathogenicity islands, but carried accessory genetic elements associated with extraintestinal infection such as iron uptake systems. Gene ontology and pathway analysis revealed reduced secondary metabolic capabilities and loss of function in terms of signalling and response to environmental cues, consistent with adaptation for the extraintestinal niche. A classification system based on machine learning identified ST416/417 as more invasive than classical gastrointestinal serovars. Genome analysis results are thus consistent with ST416/417 as a host-adapted and extraintestinal clonal population of S. enterica, which while found in porpoises without associated pathology can also cause severe opportunistic infections.

RevDate: 2021-10-22

Jiao D, Dong X, Yu Y, et al (2021)

Gene Presence/Absence Variation analysis of coronavirus family displays its pan-genomic diversity.

International journal of biological sciences, 17(14):3717-3727.

SARS-CoV-2 belongs to the coronavirus family. Comparing genomic features of viral genomes of coronavirus family can improve our understanding about SARS-CoV-2. Here we present the first pan-genome analysis of 3,932 whole genomes of 101 species out of 4 genera from the coronavirus family. We found that a total of 181 genes in the pan-genome of coronavirus family, among which only 3 genes, the S gene, M gene and N gene, are highly conserved. We also constructed a pan-genome from 23,539 whole genomes of SARS-CoV-2. There are 13 genes in total in the SARS-CoV-2 pan-genome. All of the 13 genes are core genes for SARS-CoV-2. The pan-genome of coronaviruses shows a lower level of diversity than the pan-genomes of other RNA viruses, which contain no core gene. The three highly conserved genes in coronavirus family, which are also core genes in SARS-CoV-2 pan-genome, could be potential targets in developing nucleic acid diagnostic reagents with a decreased possibility of cross-reaction with other coronavirus species.

RevDate: 2021-10-23

Whitworth DE, Sydney N, EJ Radford (2021)

Myxobacterial Genomics and Post-Genomics: A Review of Genome Biology, Genome Sequences and Related 'Omics Studies.

Microorganisms, 9(10): pii:microorganisms9102143.

Myxobacteria are fascinating and complex microbes. They prey upon other members of the soil microbiome by secreting antimicrobial proteins and metabolites, and will undergo multicellular development if starved. The genome sequence of the model myxobacterium Myxococcus xanthus DK1622 was published in 2006 and 15 years later, 163 myxobacterial genome sequences have now been made public. This explosion in genomic data has enabled comparative genomics analyses to be performed across the taxon, providing important insights into myxobacterial gene conservation and evolution. The availability of myxobacterial genome sequences has allowed system-wide functional genomic investigations into entire classes of genes. It has also enabled post-genomic technologies to be applied to myxobacteria, including transcriptome analyses (microarrays and RNA-seq), proteome studies (gel-based and gel-free), investigations into protein-DNA interactions (ChIP-seq) and metabolism. Here, we review myxobacterial genome sequencing, and summarise the insights into myxobacterial biology that have emerged as a result. We also outline the application of functional genomics and post-genomic approaches in myxobacterial research, highlighting important findings to emerge from seminal studies. The review also provides a comprehensive guide to the genomic datasets available in mid-2021 for myxobacteria (including 24 genomes that we have sequenced and which are described here for the first time).

RevDate: 2021-10-23

Kang IJ, Kim KS, Beattie GA, et al (2021)

Pan-Genome Analysis of Effectors in Korean Strains of the Soybean Pathogen Xanthomonas citri pv. glycines.

Microorganisms, 9(10): pii:microorganisms9102065.

Xanthomonas citri pv. glycines is a major pathogen of soybean in Korea. Here, we analyzed pathogenicity genes based on a comparative genome analysis of five Korean strains and one strain from the United States, 8ra. Whereas all six strains had nearly identical profiles of carbohydrate-active enzymes, they varied in diversity and number of candidate type III secretion system effector (T3SE) genes. The five Korean strains were similar in their effectors, but differed from the 8ra strain. Across the six strains, transcription activator-like effectors (TALEs) showed diverse repeat sizes and at least six forms of the repeat variable di-residue (RVD) sequences, with differences not correlated with the origin of the strains. However, a phylogenetic tree based on the alignment of RVD sequences showed two distinct clusters with 17.5 repeats, suggesting that two distinct 17.5 RVD clusters have evolved, potentially to adapt Xcg to growth on distinct soybean cultivars. The predicted effector binding elements of the TALEs fell into six groups and were strongly overlapping in sequence, suggesting evolving target specificity of the binding domains in soybean cultivars. Our findings reveal the variability and adaptability of T3SEs in the Xcg strains and enhance our understanding of Xcg pathogenicity in soybean.

RevDate: 2021-10-23

Lu W, Pei Z, Zang M, et al (2021)

Comparative Genomic Analysis of Bifidobacterium bifidum Strains Isolated from Different Niches.

Genes, 12(10): pii:genes12101504.

The potential probiotic benefits of Bifidobacterium bifidum have received increasing attention recently. We used comparative genomic analysis to explore the differences in the genome and the physiological characteristics of B. bifidum isolated from the fecal samples of Chinese adults and infants. The relationships between genotypes and phenotypes were analyzed to assess the effects of isolation sources on the genetic variation of B. bifidum. The phylogenetic tree results indicated that the phylogeny of B. bifidum may be related to the geographical features of its isolation source. B. bifidum was found to have an open pan-genome and a conserved core genome. The genetic diversity of B. bifidum is mainly reflected in carbohydrate metabolism- and immune/competition-related factors, such as the glycoside hydrolase gene family, bacteriocin operons, antibiotic resistance genes, and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas. Additionally, the type III A CRISPR-Cas system was discovered in B. bifidum for the first time. B. bifidum strains exhibited niche-specific characteristics, and the results of this study provide an improved understanding of the genetics of this species.

RevDate: 2021-10-20

Rodrigues RAL, Queiroz VF, Ghosh J, et al (2021)

Functional genomic analyses reveal an open pan-genome for the chloroviruses and a potential for genetic innovation in new isolates.

Journal of virology [Epub ahead of print].

Chloroviruses (family Phycodnaviridae) are large dsDNA viruses that infect unicellular green algae present in inland waters. These viruses have been isolated using three main chlorella-like green algal host cells, traditionally called NC64A, SAG and Pbi, revealing extensive genetic diversity. In this study, we performed a functional genomic analysis on 36 chloroviruses that infected the three different hosts. Phylogenetic reconstruction based on the DNA polymerase B family gene clustered the chloroviruses into three distinct clades. The viral pan-genome consists of 1,345 clusters of orthologous groups of genes (COGs), with 126 COGs conserved in all viruses. 368, 268 and 265 COGs are found exclusively in viruses that infect NC64A, SAG, and Pbi algal hosts, respectively. Two-thirds of the COGs have no known function, constituting the "dark pan-genome" of chloroviruses, and further studies focusing on these genes may identify important novelties. The proportion of functionally characterized COGs composing the pan- and the core-genome are similar, but those related to transcription and RNA processing, protein metabolism, and virion morphogenesis are at least 4-fold more represented in the core-genome. Bipartite network construction evidencing the COG-sharing among host-specific viruses identified 270 COGs shared by at least one virus from each of the different host groups. Finally, our results reveal an open pan-genome for chloroviruses and a well-established core-genome, indicating that the isolation of new chloroviruses can be a valuable source of genetic discovery. Importance Chloroviruses are large dsDNA viruses that infect unicellular green algae distributed worldwide in freshwater environments. They comprise a genetically diverse group of viruses; however, a comprehensive investigation of the genomic evolution of these viruses is still missing. Here we performed a functional pan-genome analysis comprising 36 chloroviruses associated with three different algal hosts in the family Chlorellaceae, referred to as zoochlorellae because of their endosymbiotic lifestyle. We identified a set of 126 highly conserved genes, most of which are related to essential functions in the viral replicative cycle. Several genes are unique to distinct isolates, resulting in an open pan-genome for chloroviruses. This profile is associated with generalist organisms, and new insights into the evolution and ecology of chloroviruses are presented. Ultimately, our results highlight the potential for genetic diversity in new isolates.

RevDate: 2021-10-20

González-Castillo A, Carballo JL, E Bautista-Guerrero (2021)

Genomics and phylogeny of the proposed phylum 'Candidatus Poribacteria' associated with the excavating sponge Thoosa mismalolli.

Antonie van Leeuwenhoek [Epub ahead of print].

Members of the proposed phylum 'Candidatus Poribacteria' are among the most abundant microorganisms in the highly diverse microbiome of the sponge mesohyl. Genomic and phylogenetic characteristics of this proposed phylum are barely known. In this study, we analyzed metagenome-assembled genomes (MAGs) obtained from the coral reef excavating sponge Thoosa mismalolli from the Mexican Pacific Ocean. Two MAGs were extracted and analyzed together with 32 MAGs and single-amplified genomes (SAGs) obtained from NCBI. The phylogenetic tree based on the sequences of 139 single-copy genes (SCG) showed two clades. Clade A (23 genomes) represented 67.7% of the total of the genomes, while clade B (11 genomes) comprised 32.3% of the genomes. The Average Nucleotide Identity (ANI) showed values between 66 and 99% for the genomes of the proposed phylum, and the pangenome of genomes revealed a total of 37,234 genes that included 1722 core gene. The number of genes used in the phylogenetic analysis increased from 28 (previous studies) to 139 (this study), which allowed a better resolution of the phylogeny of the proposed phylum. The results supported the two previously described classes, 'Candidatus Entoporibacteria' and 'Candidatus Pelagiporibacteria', and the genomes SB0101 and SB0202 obtained in this study belong to two new species of the class 'Candidatus Entoporibacteria'. This is the first comparative study that includes MAGs from a non-sponge host (Porites lutea) to elucidate the taxonomy of the poorly known Candidatus phylum in a polyphasic approach. Finally, our study also contributes to the sponge microbiome project by reporting the first MAGs of the proposed phylum 'Candidatus Poribacteria' isolated from the excavating sponge T. mismalolli.

RevDate: 2021-10-19

Douglas GM, BJ Shapiro (2021)

Genic selection within prokaryotic pangenomes.

Genome biology and evolution pii:6402011 [Epub ahead of print].

Understanding the evolutionary forces shaping prokaryotic pangenome structure is a major goal of microbial evolution research. Recent work has highlighted that a substantial proportion of accessory genes appear to confer niche-specific adaptations. This work has primarily focused on selection acting at the level of individual cells. Herein, we discuss a lower level of selection that also contributes to pangenome variation: genic selection. This refers to cases where genetic elements, rather than individual cells, are the entities under selection. The clearest examples of this form of selection are selfish mobile genetic elements, which are those that have either a neutral or deleterious effect on host fitness. We review the major classes of these and other mobile elements and discuss the characteristic features of such elements that could be under genic selection. We also discuss how genetic elements that are beneficial to hosts can also be under genic selection, a scenario that may be more prevalent but not widely appreciated, because disentangling the effects of selection at different levels (i.e., organisms vs genes) is challenging. Nonetheless, an appreciation for the potential action and implications of genic selection provides a useful conceptual lens with which to study the evolution of prokaryotic pangenomes.

RevDate: 2021-10-18

Liu H, Prajapati V, Prajapati S, et al (2021)

Comparative Genome Analysis of Bacillus amyloliquefaciens Focusing on Phylogenomics, Functional Traits, and Prevalence of Antimicrobial and Virulence Genes.

Frontiers in genetics, 12:724217.

Bacillus amyloliquefaciens is a gram-positive, nonpathogenic, endospore-forming, member of a group of free-living soil bacteria with a variety of traits including plant growth promotion, production of antifungal and antibacterial metabolites, and production of industrially important enzymes. We have attempted to reconstruct the biogeographical structure according to functional traits and the evolutionary lineage of B. amyloliquefaciens using comparative genomics analysis. All the available 96 genomes of B. amyloliquefaciens strains were curated from the NCBI genome database, having a variety of important functionalities in all sectors keeping a high focus on agricultural aspects. In-depth analysis was carried out to deduce the orthologous gene groups and whole-genome similarity. Pan genome analysis revealed that shell genes, soft core genes, core genes, and cloud genes comprise 17.09, 5.48, 8.96, and 68.47%, respectively, which demonstrates that genomes are very different in the gene content. It also indicates that the strains may have flexible environmental adaptability or versatile functions. Phylogenetic analysis showed that B. amyloliquefaciens is divided into two clades, and clade 2 is further dived into two different clusters. This reflects the difference in the sequence similarity and diversification that happened in the B. amyloliquefaciens genome. The majority of plant-associated strains of B. amyloliquefaciens were grouped in clade 2 (73 strains), while food-associated strains were in clade 1 (23 strains). Genome mining has been adopted to deduce antimicrobial resistance and virulence genes and their prevalence among all strains. The genes tmrB and yuaB codes for tunicamycin resistance protein and hydrophobic coat forming protein only exist in clade 2, while clpP, which codes for serine proteases, is only in clade 1. Genome plasticity of all strains of B. amyloliquefaciens reflects their adaption to different niches.

RevDate: 2021-10-18

Thomas P, Abdel-Glil MY, Eichhorn I, et al (2021)

Genome Sequence Analysis of Clostridium chauvoei Strains of European Origin and Evaluation of Typing Options for Outbreak Investigations.

Frontiers in microbiology, 12:732106.

Black quarter caused by Clostridium (C.) chauvoei is an important bacterial disease that affects cattle and sheep with high mortality. A comparative genomics analysis of 64 C. chauvoei strains, most of European origin and a few of non-European and unknown origin, was performed. The pangenome analysis showed limited new gene acquisition for the species. The accessory genome involved prophages and genomic islands, with variations in gene composition observed in a few strains. This limited accessory genome may indicate that the species replicates only in the host or that an active CRISPR/Cas system provides immunity to foreign genetic elements. All strains contained a CRISPR type I-B system and it was confirmed that the unique spacer sequences therein can be used to differentiate strains. Homologous recombination events, which may have contributed to the evolution of this pathogen, were less frequent compared to other related species from the genus. Pangenome single nucleotide polymorphism (SNP) based phylogeny and clustering indicate diverse clusters related to geographical origin. Interestingly the identified SNPs were mostly non-synonymous. The study demonstrates the possibility of the existence of polymorphic populations in one host, based on strain variability observed for strains from the same animal and strains from different animals of one outbreak. The study also demonstrates that new outbreak strains are mostly related to earlier outbreak strains from the same farm/region. This indicates the last common ancestor strain from one farm can be crucial to understand the genetic changes and epidemiology occurring at farm level. Known virulence factors for the species were highly conserved among the strains. Genetic elements involved in Nicotinamide adenine dinucleotide (NAD) precursor synthesis (via nadA, nadB, and nadC metabolic pathway) which are known as potential anti-virulence loci are completely absent in C. chauvoei compared to the partial inactivation in C. septicum. A novel core-genome MLST based typing method was compared to sequence typing based on CRISPR spacers to evaluate the usefulness of the methods for outbreak investigations.

RevDate: 2021-10-18

Caicedo-Montoya C, Manzo-Ruiz M, R Ríos-Estepa (2021)

Pan-Genome of the Genus Streptomyces and Prioritization of Biosynthetic Gene Clusters With Potential to Produce Antibiotic Compounds.

Frontiers in microbiology, 12:677558.

Species of the genus Streptomyces are known for their ability to produce multiple secondary metabolites; their genomes have been extensively explored to discover new bioactive compounds. The richness of genomic data currently available allows filtering for high quality genomes, which in turn permits reliable comparative genomics studies and an improved prediction of biosynthetic gene clusters (BGCs) through genome mining approaches. In this work, we used 121 genome sequences of the genus Streptomyces in a comparative genomics study with the aim of estimating the genomic diversity by protein domains content, sequence similarity of proteins and conservation of Intergenic Regions (IGRs). We also searched for BGCs but prioritizing those with potential antibiotic activity. Our analysis revealed that the pan-genome of the genus Streptomyces is clearly open, with a high quantity of unique gene families across the different species and that the IGRs are rarely conserved. We also described the phylogenetic relationships of the analyzed genomes using multiple markers, obtaining a trustworthy tree whose relationships were further validated by Average Nucleotide Identity (ANI) calculations. Finally, 33 biosynthetic gene clusters were detected to have potential antibiotic activity and a predicted mode of action, which might serve up as a guide to formulation of related experimental studies.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Liang Q, S Lonardi (2021)

Reference-agnostic representation and visualization of pan-genomes.

BMC bioinformatics, 22(1):502.

BACKGROUND: The pan-genome of a species is the union of the genes and non-coding sequences present in all individuals (cultivar, accessions, or strains) within that species.

RESULTS: Here we introduce PGV, a reference-agnostic representation of the pan-genome of a species based on the notion of consensus ordering. Our experimental results demonstrate that PGV enables an intuitive, effective and interactive visualization of a pan-genome by providing a genome browser that can elucidate complex structural genomic variations.

CONCLUSIONS: The PGV software can be installed via conda or downloaded from https://github.com/ucrbioinfo/PGV . The companion PGV browser at http://pgv.cs.ucr.edu can be tested using example bed tracks available from the GitHub page.

RevDate: 2021-10-16

Yuan S, Wang Y, Zhao F, et al (2021)

Complete Genome Sequence of Weissella confusa LM1 and Comparative Genomic Analysis.

Frontiers in microbiology, 12:749218.

The genus Weissella is attracting an increasing amount of attention because of its multiple functions and probiotic potential. In particular, the species Weissella confusa is known to have great potential in industrial applications and exhibits numerous biological functions. However, the knowledge on this bacterium in insects is not investigated. Here, we isolated and identified W. confusa as the dominant lactic acid bacteria in the gut of the migratory locust. We named this strain W. confusa LM1, which is the first genome of an insect-derived W. confusa strain with one complete chromosome and one complete plasmid. Among all W. confusa strains, W. confusa LM1 had the largest genome. Its genome was the closest to that of W. confusa 1001271B_151109_G12, a strain from human feces. Our results provided accurate evolutionary relationships of known Weissella species and W. confusa strains. Based on genomic analysis, the pan-genome of W. confusa is in an open state. Most strains of W. confusa had the unique genes, indicating that these strains can adapt to different ecological niches and organisms. However, the variation of strain-specific genes did represent significant correlations with their hosts and ecological niches. These strains were predicted to have low potential to produce secondary metabolites. Furthermore, no antibiotic resistance genes were identified. At the same time, virulence factors associated with toxin production and secretion system were not found, indicating that W. confusa strains were not sufficient to perform virulence. Our study facilitated the discovery of the functions of W. confusa LM1 in locust biology and their potential application to locust management.

RevDate: 2021-10-14

Zeng Q, Xie J, Li Y, et al (2021)

Comprehensive Genomic Analysis of the Endophytic Bacillus altitudinis Strain GLB197, a Potential Biocontrol Agent of Grape Downy Mildew.

Frontiers in genetics, 12:729603.

Bacillus has been extensively studied for agricultural application as a biocontrol agent. B. altitudinis GLB197, an endophytic bacterium isolated from grape leaves, exhibits distinctive inhibition to grape downy mildew based on unknown mechanisms. To determine the genetic traits involved in the mechanism of biocontrol and host-interaction traits, the genome sequence of GLB197 was obtained and further analyzed. The genome of B. altitudinis GLB197 consisted of one plasmid and a 3,733,835-bp circular chromosome with 41.56% G + C content, containing 3,770 protein-coding genes. Phylogenetic analysis of 17 Bacillus strains using the concatenated 1,226 single-copy core genes divided into different clusters was conducted. In addition, average nucleotide identity (ANI) values indicate that the current taxonomy of some B. pumilus group strains is incorrect. Comparative analysis of B. altitudinis GLB197 proteins with other B. altitudinis strains identified 3,157 core genes. Furthermore, we found that the pan-genome of B. altitudinis is open. The genome of B. altitudinis GLB197 contains one nonribosomal peptide synthetase (NRPS) gene cluster which was annotated as lichenysin. Interestingly, the cluster in B. altitudinis has two more genes than other Bacillus strains (lgrD and lgrB). The two genes were probably obtained via horizontal gene transfer (HGT) during the evolutionary process from Brevibacillus. Taken together, these observations enable the future application of B. altitudinis GLB197 as a biocontrol agent for control of grape downy mildew and promote our understanding of the beneficial interactions between B. altitudinis GLB197 and plants.


RJR Experience and Expertise


Robbins holds BS, MS, and PhD degrees in the life sciences. He served as a tenured faculty member in the Zoology and Biological Science departments at Michigan State University. He is currently exploring the intersection between genomics, microbial ecology, and biodiversity — an area that promises to transform our understanding of the biosphere.


Robbins has extensive experience in college-level education: At MSU he taught introductory biology, genetics, and population genetics. At JHU, he was an instructor for a special course on biological database design. At FHCRC, he team-taught a graduate-level course on the history of genetics. At Bellevue College he taught medical informatics.


Robbins has been involved in science administration at both the federal and the institutional levels. At NSF he was a program officer for database activities in the life sciences, at DOE he was a program officer for information infrastructure in the human genome project. At the Fred Hutchinson Cancer Research Center, he served as a vice president for fifteen years.


Robbins has been involved with information technology since writing his first Fortran program as a college student. At NSF he was the first program officer for database activities in the life sciences. At JHU he held an appointment in the CS department and served as director of the informatics core for the Genome Data Base. At the FHCRC he was VP for Information Technology.


While still at Michigan State, Robbins started his first publishing venture, founding a small company that addressed the short-run publishing needs of instructors in very large undergraduate classes. For more than 20 years, Robbins has been operating The Electronic Scholarly Publishing Project, a web site dedicated to the digital publishing of critical works in science, especially classical genetics.


Robbins is well-known for his speaking abilities and is often called upon to provide keynote or plenary addresses at international meetings. For example, in July, 2012, he gave a well-received keynote address at the Global Biodiversity Informatics Congress, sponsored by GBIF and held in Copenhagen. The slides from that talk can be seen HERE.


Robbins is a skilled meeting facilitator. He prefers a participatory approach, with part of the meeting involving dynamic breakout groups, created by the participants in real time: (1) individuals propose breakout groups; (2) everyone signs up for one (or more) groups; (3) the groups with the most interested parties then meet, with reports from each group presented and discussed in a subsequent plenary session.


Robbins has been engaged with photography and design since the 1960s, when he worked for a professional photography laboratory. He now prefers digital photography and tools for their precision and reproducibility. He designed his first web site more than 20 years ago and he personally designed and implemented this web site. He engages in graphic design as a hobby.

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In the mid-1970s, scientists began using DNA sequences to reexamine the history of all life. Perhaps the most startling discovery to come out of this new field—the study of life’s diversity and relatedness at the molecular level—is horizontal gene transfer (HGT), or the movement of genes across species lines. It turns out that HGT has been widespread and important; we now know that roughly eight percent of the human genome arrived sideways by viral infection—a type of HGT. In The Tangled Tree, “the grandest tale in biology….David Quammen presents the science—and the scientists involved—with patience, candor, and flair” (Nature). We learn about the major players, such as Carl Woese, the most important little-known biologist of the twentieth century; Lynn Margulis, the notorious maverick whose wild ideas about “mosaic” creatures proved to be true; and Tsutomu Wantanabe, who discovered that the scourge of antibiotic-resistant bacteria is a direct result of horizontal gene transfer, bringing the deep study of genome histories to bear on a global crisis in public health.

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E-mail: RJR8222@gmail.com

Collection of publications by R J Robbins

Reprints and preprints of publications, slide presentations, instructional materials, and data compilations written or prepared by Robert Robbins. Most papers deal with computational biology, genome informatics, using information technology to support biomedical research, and related matters.

Research Gate page for R J Robbins

ResearchGate is a social networking site for scientists and researchers to share papers, ask and answer questions, and find collaborators. According to a study by Nature and an article in Times Higher Education , it is the largest academic social network in terms of active users.

Curriculum Vitae for R J Robbins

short personal version

Curriculum Vitae for R J Robbins

long standard version

RJR Picks from Around the Web (updated 11 MAY 2018 )