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July 7, 2019

Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis.

The mutualistic symbiosis involving Glomeromycota, a distinctive phylum of early diverging Fungi, is widely hypothesized to have promoted the evolution of land plants during the middle Paleozoic. These arbuscular mycorrhizal fungi (AMF) perform vital functions in the phosphorus cycle that are fundamental to sustainable crop plant productivity. The unusual biological features of AMF have long fascinated evolutionary biologists. The coenocytic hyphae host a community of hundreds of nuclei and reproduce clonally through large multinucleated spores. It has been suggested that the AMF maintain a stable assemblage of several different genomes during the life cycle, but this genomic organization has been questioned. Here we introduce the 153-Mb haploid genome of Rhizophagus irregularis and its repertoire of 28,232 genes. The observed low level of genome polymorphism (0.43 SNP per kb) is not consistent with the occurrence of multiple, highly diverged genomes. The expansion of mating-related genes suggests the existence of cryptic sex-related processes. A comparison of gene categories confirms that R. irregularis is close to the Mucoromycotina. The AMF obligate biotrophy is not explained by genome erosion or any related loss of metabolic complexity in central metabolism, but is marked by a lack of genes encoding plant cell wall-degrading enzymes and of genes involved in toxin and thiamine synthesis. A battery of mycorrhiza-induced secreted proteins is expressed in symbiotic tissues. The present comprehensive repertoire of R. irregularis genes provides a basis for future research on symbiosis-related mechanisms in Glomeromycota.


July 7, 2019

Complete genome sequence of Staphylococcus aureus Z172, a vancomycin-intermediate and daptomycin-nonsusceptible methicillin-resistant strain isolated in Taiwan.

We report the complete genome sequence of Z172, a representative strain of sequence type 239-staphylococcal cassette chromosome mec type III (ST239-SCCmec type III) hospital-associated methicillin-resistant Staphylococcus aureus in Taiwan. Strain Z172 also exhibits a vancomycin-intermediate and daptomycin-nonsusceptible phenotype.


July 7, 2019

PBSIM: PacBio reads simulator–toward accurate genome assembly.

PacBio sequencers produce two types of characteristic reads (continuous long reads: long and high error rate and circular consensus sequencing: short and low error rate), both of which could be useful for de novo assembly of genomes. Currently, there is no available simulator that targets the specific generation of PacBio libraries.Our analysis of 13 PacBio datasets showed characteristic features of PacBio reads (e.g. the read length of PacBio reads follows a log-normal distribution). We have developed a read simulator, PBSIM, that captures these features using either a model-based or sampling-based method. Using PBSIM, we conducted several hybrid error correction and assembly tests for PacBio reads, suggesting that a continuous long reads coverage depth of at least 15 in combination with a circular consensus sequencing coverage depth of at least 30 achieved extensive assembly results.PBSIM is freely available from the web under the GNU GPL v2 license (http://code.google.com/p/pbsim/).


July 7, 2019

Complete genome sequence of Leifsonia xyli subsp. cynodontis strain DSM46306, a gram-positive bacterial pathogen of grasses.

We announce the complete genome sequence of Leifsonia xyli subsp. cynodontis, a vascular pathogen of Bermuda grass. The species also comprises Leifsonia xyli subsp. xyli, a sugarcane pathogen. Since these two subspecies have genome sequences available, a comparative analysis will contribute to our understanding of the differences in their biology and host specificity.


July 7, 2019

Draft genome of Spiribacter salinus M19-40, an abundant gammaproteobacterium in aquatic hypersaline environments.

We have previously used a de novo metagenomic assembly approach to describe the presence of an abundant gammaproteobacterium comprising nearly 15% of the microbial community in an intermediate salinity solar saltern pond. We have obtained this microbe in pure culture and describe the genome sequencing of the halophilic photoheterotrophic microbe, Spiribacter salinus M19-40.


July 7, 2019

Genome sequence of Phaeobacter caeruleus type strain (DSM 24564(T)), a surface-associated member of the marine Roseobacter clade.

In 2009 Phaeobacter caeruleus was described as a novel species affiliated with the marine Roseobacter clade, which, in turn, belongs to the class Alphaproteobacteria. The genus Phaeobacter is well known for members that produce various secondary metabolites. Here we report of putative quorum sensing systems, based on the finding of six N-acyl-homoserine lactone synthetases, and show that the blue color of P. caeruleus is probably due to the production of the secondary metabolite indigoidine. Therefore, P. caeruleus might have inhibitory effects on other bacteria. In this study the genome of the type strain DSM 24564(T) was sequenced, annotated and characterized. The 5,344,419 bp long genome with its seven plasmids contains 5,227 protein-coding genes (3,904 with a predicted function) and 108 RNA genes.


July 7, 2019

Genome sequence of a novel, newly isolated strain of guinea pig cytomegalovirus, the CIDMTR strain.

The sequence of a newly discovered isolate of guinea pig cytomegalovirus (GPCMV), the CIDMTR strain, was determined. The 232,778-nucleotide genome was generally well conserved with that of the 22122 reference strain, although some regions of substantial sequence divergence allowed annotation of strain-specific open reading frames encoding putative immune modulation gene products.


July 7, 2019

Complete genome sequence of Enterobacter sp. IIT-BT 08: A potential microbial strain for high rate hydrogen production.

Enterobacter sp. IIT-BT 08 belongs to Phylum: Proteobacteria, Class: Gammaproteobacteria, Order: Enterobacteriales, Family: Enterobacteriaceae. The organism was isolated from the leaves of a local plant near the Kharagpur railway station, Kharagpur, West Bengal, India. It has been extensively studied for fermentative hydrogen production because of its high hydrogen yield. For further enhancement of hydrogen production by strain development, complete genome sequence analysis was carried out. Sequence analysis revealed that the genome was linear, 4.67 Mbp long and had a GC content of 56.01%. The genome properties encode 4,393 protein-coding and 179 RNA genes. Additionally, a putative pathway of hydrogen production was suggested based on the presence of formate hydrogen lyase complex and other related genes identified in the genome. Thus, in the present study we describe the specific properties of the organism and the generation, annotation and analysis of its genome sequence as well as discuss the putative pathway of hydrogen production by this organism.


July 7, 2019

Multiple genome sequences of Helicobacter pylori strains of diverse disease and antibiotic resistance backgrounds from Malaysia.

Helicobacter pylori causes human gastroduodenal diseases, including chronic gastritis and peptic ulcer disease. It is also a major microbial risk factor for the development of gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Twenty-one strains with different ethnicity, disease, and antimicrobial susceptibility backgrounds were sequenced by use of Illumina HiSeq and PacBio RS platforms.


July 7, 2019

Genome sequence of Phaeobacter inhibens type strain (T5(T)), a secondary metabolite producing representative of the marine Roseobacter clade, and emendation of the species description of Phaeobacter inhibens.

Strain T5(T) is the type strain of the species Phaeobacter inhibens Martens et al. 2006, a secondary metabolite producing bacterium affiliated to the Roseobacter clade. Strain T5(T) was isolated from a water sample taken at the German Wadden Sea, southern North Sea. Here we describe the complete genome sequence and annotation of this bacterium with a special focus on the secondary metabolism and compare it with the genomes of the Phaeobacter inhibens strains DSM 17395 and DSM 24588 (2.10), selected because of the close phylogenetic relationship based on the 16S rRNA gene sequences of these three strains. The genome of strain T5(T) comprises 4,130,897 bp with 3.923 protein-coding genes and shows high similarities in genetic and genomic characteristics compared to P. inhibens DSM 17395 and DSM 24588 (2.10). Besides the chromosome, strain T5(T) possesses four plasmids, three of which show a high similarity to the plasmids of the strains DSM 17395 and DSM 24588 (2.10). Analysis of the fourth plasmid suggested horizontal gene transfer. Most of the genes on this plasmid are not present in the strains DSM 17395 and DSM 24588 (2.10) including a nitrous oxide reductase, which allows strain T5(T) a facultative anaerobic lifestyle. The G+C content was calculated from the genome sequence and differs significantly from the previously published value, thus warranting an emendation of the species description.


July 7, 2019

Genomes of “Spiribacter”, a streamlined, successful halophilic bacterium.

Thalassosaline waters produced by the concentration of seawater are widespread and common extreme aquatic habitats. Their salinity varies from that of sea water (ca. 3.5%) to saturation for NaCl (ca. 37%). Obviously the microbiota varies dramatically throughout this range. Recent metagenomic analysis of intermediate salinity waters (19%) indicated the presence of an abundant and yet undescribed gamma-proteobacterium. Two strains belonging to this group have been isolated from saltern ponds of intermediate salinity in two Spanish salterns and were named “Spiribacter”.The genomes of two isolates of “Spiribacter” have been fully sequenced and assembled. The analysis of metagenomic datasets indicates that microbes of this genus are widespread worldwide in medium salinity habitats representing the first ecologically defined moderate halophile. The genomes indicate that the two isolates belong to different species within the same genus. Both genomes are streamlined with high coding densities, have few regulatory mechanisms and no motility or chemotactic behavior. Metabolically they are heterotrophs with a subgroup II xanthorhodopsin as an additional energy source when light is available.This is the first bacterium that has been proven by culture independent approaches to be prevalent in hypersaline habitats of intermediate salinity (half a way between the sea and NaCl saturation). Predictions from the proteome and analysis of transporter genes, together with a complete ectoine biosynthesis gene cluster are consistent with these microbes having the salt-out-organic-compatible solutes type of osmoregulation. All these features are also consistent with a well-adapted fully planktonic microbe while other halophiles with more complex genomes such as Salinibacter ruber might have particle associated microniches.


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