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July 7, 2019

Complete genome sequence of Bacillus subtilis strain PY79.

Bacillus subtilis is a Gram-positive soil-dwelling and endospore-forming bacterium in the phylum Firmicutes. B. subtilis strain PY79 is a prototrophic laboratory strain that has been highly used for studying a wide variety of cellular pathways. Here, we announce the complete whole-genome sequence of B. subtilis PY79.


July 7, 2019

Finished bacterial genomes from shotgun sequence data.

Exceptionally accurate genome reference sequences have proven to be of great value to microbial researchers. Thus, to date, about 1800 bacterial genome assemblies have been “finished” at great expense with the aid of manual laboratory and computational processes that typically iterate over a period of months or even years. By applying a new laboratory design and new assembly algorithm to 16 samples, we demonstrate that assemblies exceeding finished quality can be obtained from whole-genome shotgun data and automated computation. Cost and time requirements are thus dramatically reduced.


July 7, 2019

A hybrid approach for the automated finishing of bacterial genomes.

Advances in DNA sequencing technology have improved our ability to characterize most genomic diversity. However, accurate resolution of large structural events is challenging because of the short read lengths of second-generation technologies. Third-generation sequencing technologies, which can yield longer multikilobase reads, have the potential to address limitations associated with genome assembly. Here we combine sequencing data from second- and third-generation DNA sequencing technologies to assemble the two-chromosome genome of a recent Haitian cholera outbreak strain into two nearly finished contigs at >99.9% accuracy. Complex regions with clinically relevant structure were completely resolved. In separate control assemblies on experimental and simulated data for the canonical N16961 cholera reference strain, we obtained 14 scaffolds of greater than 1 kb for the experimental data and 8 scaffolds of greater than 1 kb for the simulated data, which allowed us to correct several errors in contigs assembled from the short-read data alone. This work provides a blueprint for the next generation of rapid microbial identification and full-genome assembly.


July 7, 2019

Complete genome sequence of Liberibacter crescens BT-1.

Liberibacter crescens BT-1, a Gram-negative, rod-shaped bacterial isolate, was previously recovered from mountain papaya to gain insight on Huanglongbing (HLB) and Zebra Chip (ZC) diseases. The genome of BT-1 was sequenced at the Interdisciplinary Center for Biotechnology Research (ICBR) at the University of Florida. A finished assembly and annotation yielded one chromosome with a length of 1,504,659 bp and a G+C content of 35.4%. Comparison to other species in the Liberibacter genus, L. crescens has many more genes in thiamine and essential amino acid biosynthesis. This likely explains why L. crescens BT-1 is culturable while the known Liberibacter strains have not yet been cultured. Similar to Candidatus L. asiaticus psy62, the L. crescens BT-1 genome contains two prophage regions.


July 7, 2019

Absence of genome reduction in diverse, facultative endohyphal bacteria.

Fungi interact closely with bacteria, both on the surfaces of the hyphae and within their living tissues (i.e. endohyphal bacteria, EHB). These EHB can be obligate or facultative symbionts and can mediate diverse phenotypic traits in their hosts. Although EHB have been observed in many lineages of fungi, it remains unclear how widespread and general these associations are, and whether there are unifying ecological and genomic features can be found across EHB strains as a whole. We cultured 11 bacterial strains after they emerged from the hyphae of diverse Ascomycota that were isolated as foliar endophytes of cupressaceous trees, and generated nearly complete genome sequences for all. Unlike the genomes of largely obligate EHB, the genomes of these facultative EHB resembled those of closely related strains isolated from environmental sources. Although all analysed genomes encoded structures that could be used to interact with eukaryotic hosts, pathways previously implicated in maintenance and establishment of EHB symbiosis were not universally present across all strains. Independent isolation of two nearly identical pairs of strains from different classes of fungi, coupled with recent experimental evidence, suggests horizontal transfer of EHB across endophytic hosts. Given the potential for EHB to influence fungal phenotypes, these genomes could shed light on the mechanisms of plant growth promotion or stress mitigation by fungal endophytes during the symbiotic phase, as well as degradation of plant material during the saprotrophic phase. As such, these findings contribute to the illumination of a new dimension of functional biodiversity in fungi.


July 7, 2019

Cultivation of a chemoautotroph from the SUP05 clade of marine bacteria that produces nitrite and consumes ammonium.

Marine oxygen minimum zones (OMZs) are expanding regions of intense nitrogen cycling. Up to half of the nitrogen available for marine organisms is removed from the ocean in these regions. Metagenomic studies have identified an abundant group of sulfur-oxidizing bacteria (SUP05) with the genetic potential for nitrogen cycling and loss in OMZs. However, SUP05 have defied cultivation and their physiology remains untested. We cultured, sequenced and tested the physiology of an isolate from the SUP05 clade. We describe a facultatively anaerobic sulfur-oxidizing chemolithoautotroph that produces nitrite and consumes ammonium under anaerobic conditions. Genetic evidence that closely related strains are abundant at nitrite maxima in OMZs suggests that sulfur-oxidizing chemoautotrophs from the SUP05 clade are a potential source of nitrite, fueling competing nitrogen removal processes in the ocean.


July 7, 2019

Quantum changes in Helicobacter pylori gene expression accompany host-adaptation.

Helicobacter pylori is a highly successful gastric pathogen. High genomic plasticity allows its adaptation to changing host environments. Complete genomes of H. pylori clinical isolate UM032 and its mice-adapted serial derivatives 298 and 299, generated using both PacBio RS and Illumina MiSeq sequencing technologies, were compared to identify novel elements responsible for host-adaptation. The acquisition of a jhp0562-like allele, which encodes for a galactosyltransferase, was identified in the mice-adapted strains. Our analysis implies a new ß-1,4-galactosyltransferase role for this enzyme, essential for Ley antigen expression. Intragenomic recombination between babA and babB genes was also observed. Further, we expanded on the list of candidate genes whose expression patterns have been mediated by upstream homopolymer-length alterations to facilitate host adaption. Importantly, greater than four-fold reduction of mRNA levels was demonstrated in five genes. Among the down-regulated genes, three encode for outer membrane proteins, including BabA, BabB and HopD. As expected, a substantial reduction in BabA protein abundance was detected in mice-adapted strains 298 and 299 via Western analysis. Our results suggest that the expression of Ley antigen and reduced outer membrane protein expressions may facilitate H. pylori colonisation of mouse gastric epithelium.© The Author 2016. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.


July 7, 2019

Genomic analysis of the multi-drug-resistant clinical isolate Myroides odoratimimus PR63039.

Myroides odoratimimus (M. odoratimimus) has been gradually implicated as an important nosocomial pathogen that poses a serious health threat to immunocompromised patients owing to its multi-drug resistance. However, the resistance mechanism is currently unclear. To clarify the antibiotic resistance and infectivity mechanisms of M. odoratimimus, whole genome sequencing was performed on the multi-drug-resistant M. odoratimimus strain PR63039. The genome sequence was completed with single molecule real-time (SMRT) technologies. Then, annotation was performed using RAST and IMG-ER. A number of databases and software programs were used to analyze the genomic characteristics, including GC-Profile, ISfinder, CG viewer, ARDB, CARD, ResFinder, the VFDB database, PHAST and Progressive Mauve. The M. odoratimimus PR63039 genome consisted of a chromosome and a plasmid. The genome contained a large number of resistance genes and virulence factors. The distribution of the resistance genes was distinctive, and a resistance region named MY63039-RR was found. The subsystem features generated by RAST indicated that the annotated genome had 108 genes that were potentially involved in virulence, disease and defense, all of which had strong associations with resistance and pathogenicity. The prophage analysis showed two incomplete prophages in the genome. The genomic analysis of M. odoratimimus PR63039 partially clarified its antibiotic resistance mechanisms and virulence factors. Obtaining a clear understanding of its genomic characteristics will be conducive to the management of multidrug-resistant M. odoratimimus.


July 7, 2019

Comparative genomics of extrachromosomal elements in Bacillus thuringiensis subsp. israelensis.

Bacillus thuringiensis subsp. israelensis is one of the most important microorganisms used against mosquitoes. It was intensively studied following its discovery and became a model bacterium of the B. thuringiensis species. Those studies focused on toxin genes, aggregation-associated conjugation, linear genome phages, etc. Recent announcements of genomic sequences of different strains have not been explicitly related to the biological properties studied. We report data on plasmid content analysis of four strains using ultra-high-throughput sequencing. The strains were commercial product isolates, with their putative ancestor and type B. thuringiensis subsp. israelensis strain sequenced earlier. The assembled contigs corresponding to published and novel data were assigned to plasmids described earlier in B. thuringiensis subsp. israelensis and other B. thuringiensis strains. A new 360 kb plasmid was identified, encoding multiple transporters, also found in most of the earlier sequenced strains. Our genomic data show the presence of two toxin-coding plasmids of 128 and 100 kb instead of the reported 225 kb plasmid, a co-integrate of the former two. In two of the sequenced strains, only a 100 kb plasmid was present. Some heterogeneity exists in the small plasmid content and structure between strains. These data support the perception of active plasmid exchange among B. thuringiensis subsp. israelensis strains in nature. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.


July 7, 2019

Detection, isolation and characterization of Fusobacterium gastrosuis sp. nov. colonizing the stomach of pigs.

Nine strains of a novel Fusobacterium sp. were isolated from the stomach of 6-8 months old and adult pigs. The isolates were obligately anaerobic, although they endured 2h exposure to air. Phylogenetic analysis based on 16S rRNA and gyrase B genes demonstrated that the isolates showed high sequence similarity with Fusobacterium mortiferum, Fusobacterium ulcerans, Fusobacterium varium, Fusobacterium russii and Fusobacterium necrogenes, but formed a distinct lineage in the genus Fusobacterium. Comparative analysis of the genome of the type strain of this novel Fusobacterium sp. confirmed that it is different from other recognized Fusobacterium spp. DNA-DNA hybridization, fingerprinting and genomic %GC determination further supported the conclusion that the isolates belong to a new, distinct species. The isolates were also distinguishable from these and other Fusobacterium spp. by phenotypical characterization. The strains produced indole and exhibited proline arylamidase and glutamic acid decarboxylase activity. They did not hydrolyse esculin, did not exhibit pyroglutamic acid arylamidase, valine arylamidase, a-galactosidase, ß-galactosidase, ß-galactosidase-6-phosphate or a-glucosidase activity nor produced acid from cellobiose, glucose, lactose, mannitol, mannose, maltose, raffinose, saccharose, salicin or trehalose. The major fatty acids were C16:0 and C18:1?9c. The name Fusobacterium gastrosuis sp. nov. is proposed for the novel isolates with the type strain CDW1(T) (=DSM 101753(T)=LMG 29236(T)). We also demonstrated that Clostridium rectum and mortiferum Fusobacterium represent the same species, with nomenclatural priority for the latter. Copyright © 2016 Elsevier GmbH. All rights reserved.


July 7, 2019

Evolutionary origins of the emergent ST796 clone of vancomycin resistant Enterococcus faecium.

From early 2012, a novel clone of vancomycin resistant Enterococcus faecium (assigned the multi locus sequence type ST796) was simultaneously isolated from geographically separate hospitals in south eastern Australia and New Zealand. Here we describe the complete genome sequence of Ef_aus0233, a representative ST796 E. faecium isolate. We used PacBio single molecule real-time sequencing to establish a high quality, fully assembled genome comprising a circular chromosome of 2,888,087 bp and five plasmids. Comparison of Ef_aus0233 to other E. faecium genomes shows Ef_aus0233 is a member of the epidemic hospital-adapted lineage and has evolved from an ST555-like ancestral progenitor by the accumulation or modification of five mosaic plasmids and five putative prophage, acquisition of two cryptic genomic islands, accrued chromosomal single nucleotide polymorphisms and a 80 kb region of recombination, also gaining Tn1549 and Tn916, transposons conferring resistance to vancomycin and tetracycline respectively. The genomic dissection of this new clone presented here underscores the propensity of the hospital E. faecium lineage to change, presumably in response to the specific conditions of hospital and healthcare environments.


July 7, 2019

Burkholderia humptydooensis sp. nov., a new species related to Burkholderia thailandensis and the fifth member of the Burkholderia pseudomallei complex.

During routine screening for Burkholderia pseudomallei from water wells in northern Australia in areas where it is endemic, Gram-negative bacteria (strains MSMB43(T), MSMB121, and MSMB122) with a similar morphology and biochemical pattern to B. pseudomallei and B. thailandensis were coisolated with B. pseudomallei on Ashdown’s selective agar. To determine the exact taxonomic position of these strains and to distinguish them from B. pseudomallei and B. thailandensis, they were subjected to a series of phenotypic and molecular analyses. Biochemical and fatty acid methyl ester analysis was unable to distinguish B. humptydooensis sp. nov. from closely related species. With matrix-assisted laser desorption ionization-time of flight analysis, all isolates grouped together in a cluster separate from other Burkholderia spp. 16S rRNA and recA sequence analyses demonstrated phylogenetic placement for B. humptydooensis sp. nov. in a novel clade within the B. pseudomallei group. Multilocus sequence typing (MLST) analysis of the three isolates in comparison with MLST data from 3,340 B. pseudomallei strains and related taxa revealed a new sequence type (ST318). Genome-to-genome distance calculations and the average nucleotide identity of all isolates to both B. thailandensis and B. pseudomallei, based on whole-genome sequences, also confirmed B. humptydooensis sp. nov. as a novel Burkholderia species within the B. pseudomallei complex. Molecular analyses clearly demonstrated that strains MSMB43(T), MSMB121, and MSMB122 belong to a novel Burkholderia species for which the name Burkholderia humptydooensis sp. nov. is proposed, with the type strain MSMB43(T) (American Type Culture Collection BAA-2767; Belgian Co-ordinated Collections of Microorganisms LMG 29471; DDBJ accession numbers CP013380 to CP013382).IMPORTANCEBurkholderia pseudomallei is a soil-dwelling bacterium and the causative agent of melioidosis. The genus Burkholderia consists of a diverse group of species, with the closest relatives of B. pseudomallei referred to as the B. pseudomallei complex. A proposed novel species, B. humptydooensis sp. nov., was isolated from a bore water sample from the Northern Territory in Australia. B. humptydooensis sp. nov. is phylogenetically distinct from B. pseudomallei and other members of the B. pseudomallei complex, making it the fifth member of this important group of bacteria. Copyright © 2017 Tuanyok et al.


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