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July 7, 2019

Targeted disruption of the polyketide synthase gene pks15 affects virulence against insects and phagocytic survival in the fungus Beauveria bassiana.

The reducing clade III polyketide synthase genes, including pks15, are highly conserved among entomopathogenic fungi. To examine the function of pks15, we used targeted disruption to investigate the impact of Beauveria bassiana pks15 on insect pathogenesis. Southern analysis verified that the ?pks15 mutant was disrupted by a single integration of the transformation cassette at the pks15 locus. The ?pks15 mutant had a slight reduction in radial growth, and it produced fewer spores. Our insect bioassays indicated the ?pks15 mutant to be significantly reduced in virulence against beet armyworms compared to wild type (WT), which could be partially accounted for by its markedly decreased ability to survive phagocytosis. Total haemocyte count decreased sharply by 50-fold from days 1-3 post-inoculation in insects infected with WT, compared to a 5-fold decrease in the ?pks15 mutant. The mutant also produced fewer hemolymph hyphal bodies than WT by 3-fold. In co-culture studies with amoebae that have phagocytic ability similar to that of insect haemocytes, at 48 h the mortality rate of amoebae engulfing ?pks15 decreased by 72 %, and ?pks15 CFU decreased by 83 % compared to co-culture with WT. Thus, the ?pks15 mutant had a reduced ability to cope with phagocytosis and highly reduced virulence in an insect host. These data elucidate a mechanism of insect pathogenesis associated with polyketide biosynthesis. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

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July 7, 2019

Complete genome sequence of Bacillus velezensis LM2303, a biocontrol strain isolated from the dung of wild yak inhabited Qinghai-Tibet plateau.

Bacillus velezensis LM2303 is a biocontrol strain with a broad inhibitory spectrum against plant pathogens, isolated from the dung of wild yak inhabited Qinghai-Tibet plateau, China. Here we present its complete genome sequence, which consists of a single, circular chromosome of 3,989,393bp with a 46.68% G+C content. Genome analysis revealed genes encoding specialized functions for the biosynthesis of antifungal metabolites and antibacterial metabolites, the promotion of plant growth, the alleviation of oxidative stress and nutrient utilization. And the biosynthesis of antimicrobial metabolites in strain LM2303 was confirmed by biochemical analysis, while its plant growth promoting traits were confirmed by inoculation tests. Our results will establish a better foundation for further studies and biocontrol application of B. velezensis LM2303. Copyright © 2017 Elsevier B.V. All rights reserved.

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July 7, 2019

First complete genome sequence of Bacillus glycinifermentans B-27.

The first complete genome sequence of Bacillus glycinifermentans B-27 was determined by SMRT sequencing generating a genome sequence with a total length of 4,607,442 bases. Based on this sequence 4738 protein-coding sequences were predicted and used to identify gene clusters that are related to the production of secondary metabolites such as Lichenysin, Bacillibactin and Bacitracin. This genomic potential combined with the ability of B. glycinifermentans B-27 to grown in bile containing media might contribute to a future application of this strain as probiotic in productive livestock potentially inhibiting competing and pathogenic organisms. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

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July 7, 2019

Complete genome sequence of the thermophilic bacterium Geobacillus subterraneus KCTC 3922(T) as a potential denitrifier.

Denitrification is a crucial process for the global nitrogen cycle through the reduction of nitrates by heterotrophic bacteria. Denitrifying microorganisms play an important role in eliminating fixed nitrogen pollutants from the ecosystem, concomitant with N2O emission. Although many microbial denitrifiers have been identified, little is known about the denitrifying ability of the genus Geobacillus. Here, we report the first complete genome sequences of Geobacillus subterraneus KCTC 3922(T), isolated from Liaohe oil field in China, and G. thermodenitrificans KCTC 3902(T). The strain KCTC 3922(T) contains a complete set of genes involved in denitrification, cofactor biogenesis, and transport systems, which is consistent with a denitrifying activity. On the other hand, G. thermodenitrificans KCTC 3902(T) exhibited no denitrifying activity probably due to the lack of molybdnumtransferase (moeA) and nitrite transporter (nirC) genes. Therefore, comparative genome analysis of Geobacillus strains highlights the potential impact on treatment of nitrate-contaminated environments. Copyright © 2017 Elsevier B.V. All rights reserved.

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July 7, 2019

Complete genome sequence of a denitrifying bacterium, Pseudomonas sp. CC6-YY-74, isolated from Arctic Ocean sediment

Pseudomonas sp. CC6-YY-74, a psychrotrophic, denitrifying bacterium isolated from Arctic Ocean sediment, uses NO3- or NH4+ as the sole nitrogen source to grow at low temperatures. Here we described the complete genome of Pseudomonas sp. CC6-YY-74. The genome has one circular chromosome of 5,040,792 bp (61.73 mol% G + C content), consisting of 4747 coding genes, 68 tRNA genes, as well as six rRNA operons as 16S-23S-5S rRNA. According to the annotation results, strain CC6-YY-74 encodes 52 proteins related to nitrogen metabolism, including a complete denitrifying pathway, and more than 20 kinds of hydrolytic enzymes.

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July 7, 2019

Genomesequencing of Ralstonia solanacearum CQPS-1, a phylotype I strain collected from a highland area with continuous cropping of tobacco.

Ralstonia solanacearum, an agent of bacterial wilt, is a highly variable species with a broad host range and wide geographic distribution. As a species complex, it has extensive genetic diversity and its living environment is polymorphic like the lowland and the highland area, so more genomes are needed for studying population evolution and environment adaptation. In this paper, we reported the genome sequencing of R. solanacearum strain CQPS-1 isolated from wilted tobacco in Pengshui, Chongqing, China, a highland area with severely acidified soil and continuous cropping of tobacco more than 20 years. The comparative genomic analysis among different R. solanacearum strains was also performed. The completed genome size of CQPS-1 was 5.89 Mb and contained the chromosome (3.83 Mb) and the megaplasmid (2.06 Mb). A total of 5229 coding sequences were predicted (the chromosome and megaplasmid encoded 3573 and 1656 genes, respectively). A comparative analysis with eight strains from four phylotypes showed that there was some variation among the species, e.g., a large set of specific genes in CQPS-1. Type III secretion system gene cluster (hrp gene cluster) was conserved in CQPS-1 compared with the reference strain GMI1000. In addition, most genes coding core type III effectors were also conserved with GMI1000, but significant gene variation was found in the gene ripAA: the identity compared with strain GMI1000 was 75% and the hrpII box promoter in the upstream had significantly mutated. This study provided a potential resource for further understanding of the relationship between variation of pathogenicity factors and adaptation to the host environment.

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July 7, 2019

Complete genome sequence of Bacillus sp. 275, producing extracellular cellulolytic, xylanolytic and ligninolytic enzymes.

Technologies for degradation of three major components of lignocellulose (e.g. cellulose, hemicellulose and lignin) are needed to efficiently utilize lignocellulose. Here, we report Bacillus sp. 275 isolated from a mudflat exhibiting various lignocellulolytic activities including cellulase, xylanase, laccase and peroxidase in the cell culture supernatant. The complete genome of Bacillus sp. 275 strain contains 3832 protein cording sequences and an average G+C content of 46.32% on one chromosome (4045,581bp) and one plasmid (6389bp). The genes encoding enzymes related to the degradation of cellulose, xylan and lignin were detected in the Bacillus sp. 275 genome. In addition, the genes encoding glucosidases that hydrolyze starch, mannan, galactoside and arabinan were also found in the genome, implying that Bacillus sp. 275 has potentially a wide range of uses in the degradation of polysaccharide in lignocellulosic biomasses. Copyright © 2017 Elsevier B.V. All rights reserved.

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July 7, 2019

Complete genome sequence and analysis of three kinds of ß-agarase of Cellulophaga lytica DAU203 isolated from marine sediment.

Cellulophaga lytica DAU203 (KACC 19187), isolated from the marine sediment in Korea, has a strong ability to degrade agar. The genome of C. lytica DAU203 contains a single chromosome that is 3,952,957bp in length, with 32.02% G+C contents. The genomic information predicted that the DAU203 has the potential to be utilized in various enzymatic industries. Copyright © 2017. Published by Elsevier B.V.

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July 7, 2019

The complete genome sequence of Bacillus velezensis 9912D reveals its biocontrol mechanism as a novel commercial biological fungicide agent.

A Bacillus sp. 9912 mutant, 9912D, was approved as a new biological fungicide agent by the Ministry of Agriculture of the People’s Republic of China in 2016 owing to its excellent inhibitory effect on various plant pathogens and being environment-friendly. Here, we present the genome of 9912D with a circular chromosome having 4436 coding DNA sequences (CDSs), and a circular plasmid encoding 59 CDSs. This strain was finally designated as Bacillus velezensis based on phylogenomic analyses. Genome analysis revealed a total of 19 candidate gene clusters involved in secondary metabolite biosynthesis, including potential new type II lantibiotics. The absence of fengycin biosynthetic gene cluster is noteworthy. Our data offer insights into the genetic, biological and physiological characteristics of this strain and aid in deeper understanding of its biocontrol mechanism. Copyright © 2017 Elsevier B.V. All rights reserved.

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July 7, 2019

Analysis of the genome and mobilome of a dissimilatory arsenate reducing Aeromonas sp. O23A reveals multiple mechanisms for heavy metal resistance and metabolism.

Aeromonas spp. are among the most ubiquitous microorganisms, as they have been isolated from different environmental niches including waters, soil, as well as wounds and digestive tracts of poikilothermic animals and humans. Although much attention has been paid to the pathogenicity of Aeromonads, the role of these bacteria in environmentally important processes, such as transformation of heavy metals, remains to be discovered. Therefore, the aim of this study was a detailed genomic characterization of Aeromonas sp. O23A, the first representative of this genus capable of dissimilatory arsenate reduction. The strain was isolated from microbial mats from the Zloty Stok mine (SW Poland), an environment strongly contaminated with arsenic. Previous physiological studies indicated that O23A may be involved in both mobilization and immobilization of this metalloid in the environment. To discover the molecular basis of the mechanisms behind the observed abilities, the genome of O23A (~5.0 Mbp) was sequenced and annotated, and genes for arsenic respiration, heavy metal resistance (hmr) and other phenotypic traits, including siderophore production, were identified. The functionality of the indicated gene modules was assessed in a series of minimal inhibitory concentration analyses for various metals and metalloids, as well as mineral dissolution experiments. Interestingly, comparative analyses revealed that O23A is related to a fish pathogen Aeromonas salmonicida subsp. salmonicida A449 which, however, does not carry genes for arsenic respiration. This indicates that the dissimilatory arsenate reduction ability may have been lost during genome reduction in pathogenic strains, or acquired through horizontal gene transfer. Therefore, particular emphasis was placed upon the mobilome of O23A, consisting of four plasmids, a phage, and numerous transposable elements, which may play a role in the dissemination of hmr and arsenic metabolism genes in the environment. The obtained results indicate that Aeromonas sp. O23A is well-adapted to the extreme environmental conditions occurring in the Zloty Stok mine. The analysis of genome encoded traits allowed for a better understanding of the mechanisms of adaptation of the strain, also with respect to its presumable role in colonization and remediation of arsenic-contaminated waters, which may never have been discovered based on physiological analyses alone.

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July 7, 2019

Whole-genome de novo sequencing of wood rot fungus Fomitopsis palustris (ATCC62978) with both a cellulolytic and ligninolytic enzyme system.

Fomitopsis palustris is a model brown rot fungus causing destructive wood decay based on the cellulase system. Endoglucanase secreted by F. palustris hydrolyzes cellulose in both the crystalline and amorphous form. In this study, whole-genome sequencing was conducted to identify genes related to F. palustris cellulose degradation and their functions. We determined the 43-Mb complete draft genome of F. palustris (ATCC 62978), comprising 14,592 predicted gene models. Gene annotation provided crucial information about the location and function of protein-encoding genes. Three types of endoglucanases were expressed: endo-1,3-beta-glucanase, endo-1,4-beta-d-glucanase, and endoglucanase. In addition, various ligninolytic enzymes such as laccase, aromatic compound dioxygenase, and aryl alcohol dehydrogenase were expressed in F. palustris (ATCC 62978). Colony polymerase chain reaction (PCR) indicated that the endo-1,4-beta-d-glucanase gene comprises 732bp. Optimization of the expression conditions of endoglucanase by real-time PCR revealed that endoglucanase was highly expressed after 7days in all conditions, which was secreted during the secondary metabolism. Studies for large-scale cellulase production from this fungus and investigation of its ligninolytic system will promote its extensive use in various applications. The genomic information determined herein provides a basis for molecular genetics studies to understand the genome functions of F. palustris (ATCC 62978). Copyright © 2017 Elsevier B.V. All rights reserved.

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July 7, 2019

Chromosome-level genome assembly and transcriptome of the green alga Chromochloris zofingiensis illuminates astaxanthin production.

Microalgae have potential to help meet energy and food demands without exacerbating environmental problems. There is interest in the unicellular green alga Chromochloris zofingiensis, because it produces lipids for biofuels and a highly valuable carotenoid nutraceutical, astaxanthin. To advance understanding of its biology and facilitate commercial development, we present a C. zofingiensis chromosome-level nuclear genome, organelle genomes, and transcriptome from diverse growth conditions. The assembly, derived from a combination of short- and long-read sequencing in conjunction with optical mapping, revealed a compact genome of ~58 Mbp distributed over 19 chromosomes containing 15,274 predicted protein-coding genes. The genome has uniform gene density over chromosomes, low repetitive sequence content (~6%), and a high fraction of protein-coding sequence (~39%) with relatively long coding exons and few coding introns. Functional annotation of gene models identified orthologous families for the majority (~73%) of genes. Synteny analysis uncovered localized but scrambled blocks of genes in putative orthologous relationships with other green algae. Two genes encoding beta-ketolase (BKT), the key enzyme synthesizing astaxanthin, were found in the genome, and both were up-regulated by high light. Isolation and molecular analysis of astaxanthin-deficient mutants showed that BKT1 is required for the production of astaxanthin. Moreover, the transcriptome under high light exposure revealed candidate genes that could be involved in critical yet missing steps of astaxanthin biosynthesis, including ABC transporters, cytochrome P450 enzymes, and an acyltransferase. The high-quality genome and transcriptome provide insight into the green algal lineage and carotenoid production.

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July 7, 2019

BusyBee Web: metagenomic data analysis by bootstrapped supervised binning and annotation.

Metagenomics-based studies of mixed microbial communities are impacting biotechnology, life sciences and medicine. Computational binning of metagenomic data is a powerful approach for the culture-independent recovery of population-resolved genomic sequences, i.e. from individual or closely related, constituent microorganisms. Existing binning solutions often require a priori characterized reference genomes and/or dedicated compute resources. Extending currently available reference-independent binning tools, we developed the BusyBee Web server for the automated deconvolution of metagenomic data into population-level genomic bins using assembled contigs (Illumina) or long reads (Pacific Biosciences, Oxford Nanopore Technologies). A reversible compression step as well as bootstrapped supervised binning enable quick turnaround times. The binning results are represented in interactive 2D scatterplots. Moreover, bin quality estimates, taxonomic annotations and annotations of antibiotic resistance genes are computed and visualized. Ground truth-based benchmarks of BusyBee Web demonstrate comparably high performance to state-of-the-art binning solutions for assembled contigs and markedly improved performance for long reads (median F1 scores: 70.02-95.21%). Furthermore, the applicability to real-world metagenomic datasets is shown. In conclusion, our reference-independent approach automatically bins assembled contigs or long reads, exhibits high sensitivity and precision, enables intuitive inspection of the results, and only requires FASTA-formatted input. The web-based application is freely accessible at: https://ccb-microbe.cs.uni-saarland.de/busybee.© The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

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July 7, 2019

Sequencing a piece of history: complete genome sequence of the original Escherichia coli strain.

In 1885, Theodor Escherich first described the Bacillus coli commune, which was subsequently renamed Escherichia coli. We report the complete genome sequence of this original strain (NCTC 86). The 5?144?392?bp circular chromosome encodes the genes for 4805 proteins, which include antigens, virulence factors, antimicrobial-resistance factors and secretion systems, of a commensal organism from the pre-antibiotic era. It is located in the E. coli A subgroup and is closely related to E. coli K-12 MG1655. E. coli strain NCTC 86 and the non-pathogenic K-12, C, B and HS strains share a common backbone that is largely co-linear. The exception is a large 2?803?932?bp inversion that spans the replication terminus from gmhB to clpB. Comparison with E. coli K-12 reveals 41 regions of difference (577?351?bp) distributed across the chromosome. For example, and contrary to current dogma, E. coli NCTC 86 includes a nine gene sil locus that encodes a silver-resistance efflux pump acquired before the current widespread use of silver nanoparticles as an antibacterial agent, possibly resulting from the widespread use of silver utensils and currency in Germany in the 1800s. In summary, phylogenetic comparisons with other E. coli strains confirmed that the original strain isolated by Escherich is most closely related to the non-pathogenic commensal strains. It is more distant from the root than the pathogenic organisms E. coli 042 and O157?:?H7; therefore, it is not an ancestral state for the species.

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July 7, 2019

Gas fermentation: cellular engineering possibilities and scale up.

Low carbon fuels and chemicals can be sourced from renewable materials such as biomass or from industrial and municipal waste streams. Gasification of these materials allows all of the carbon to become available for product generation, a clear advantage over partial biomass conversion into fermentable sugars. Gasification results into a synthesis stream (syngas) containing carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2) and nitrogen (N2). Autotrophy-the ability to fix carbon such as CO2 is present in all domains of life but photosynthesis alone is not keeping up with anthropogenic CO2 output. One strategy is to curtail the gaseous atmospheric release by developing waste and syngas conversion technologies. Historically microorganisms have contributed to major, albeit slow, atmospheric composition changes. The current status and future potential of anaerobic gas-fermenting bacteria with special focus on acetogens are the focus of this review.

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