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July 7, 2019

Genome evolution to penicillin resistance in serotype 3 Streptococcus pneumoniae by capsular switching.

Streptococcus pneumoniae isolates of serotype 3 were collected from cases of invasive pneumococcal disease (n= 124) throughout Japan between April 2010 and March 2013. A penicillin-resistantS. pneumoniae(PRSP) isolate from an adult patient, strain KK0981 of serotype 3, was identified among these strains. Whole-genome analysis characterized this PRSP as a recombinant strain derived from PRSP of serotype 23F with thecpslocus (20.3 kb) replaced by that of a penicillin-susceptible strain of serotype 3. Copyright © 2017 American Society for Microbiology.

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July 7, 2019

De novo whole-genome sequencing of the wood rot fungus Polyporus brumalis, which exhibits potential terpenoid metabolism.

Polyporus brumalis is able to synthesize several sesquiterpenes during fungal growth. Using a single-molecule real-time sequencing platform, we present the 53-Mb draft genome of P. brumalis, which contains 6,231 protein-coding genes. Gene annotation and isolation support genetic information, which can increase the understanding of sesquiterpene metabolism in P. brumalis. Copyright © 2017 Lee et al.

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July 7, 2019

Comparative genomic and phylogenetic analysis of a toxigenic clinical isolate of Corynebacterium diphtheriae strain B-D-16-78 from Malaysia.

In this study, we report the comparative genomics and phylogenetic analysis of Corynebacterium diphtheriae strain B-D-16-78 that was isolated from a clinical specimen in 2016. The complete genome of C. diphtheriae strain B-D-16-78 was sequenced using PacBio Single Molecule, Real-Time sequencing technology and consists of a 2,474,151-bp circular chromosome with an average GC content of 53.56%. The core genome of C. diphtheriae was also deduced from a total of 74 strains with complete or draft genome sequences and the core genome-based phylogenetic analysis revealed close genetic relationship among strains that shared the same MLST allelic profile. In the context of CRISPR-Cas system, which confers adaptive immunity against re-invading DNA, 73 out of 86 spacer sequences were found to be unique to Malaysian strains which harboured only type-II-C and/or type-I-E-a systems. A total of 48 tox genes which code for the diphtheria toxin were retrieved from the 74 genomes and with the exception of one truncated gene, only nucleotide substitutions were detected when compared to the tox gene sequence of PW8. More than half were synonymous substitution and only two were nonsynonymous substitutions whereby H24Y was predicted to have a damaging effect on the protein function whilst T262V was predicted to be tolerated. Both toxigenic and non-toxigenic toxin-gene bearing strains have been isolated in Malaysia but the repeated isolation of toxigenic strains with the same MLST profile suggests the possibility of some of these strains may be circulating in the population. Hence, efforts to increase herd immunity should be continued and supported by an effective monitoring and surveillance system to track, manage and control outbreak of cases. Copyright © 2017 Elsevier B.V. All rights reserved.

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July 7, 2019

Phenotypic and genomic comparison of Mycobacterium aurum and surrogate model species to Mycobacterium tuberculosis: implications for drug discovery.

Tuberculosis (TB) is caused by Mycobacterium tuberculosis and represents one of the major challenges facing drug discovery initiatives worldwide. The considerable rise in bacterial drug resistance in recent years has led to the need of new drugs and drug regimens. Model systems are regularly used to speed-up the drug discovery process and circumvent biosafety issues associated with manipulating M. tuberculosis. These include the use of strains such as Mycobacterium smegmatis and Mycobacterium marinum that can be handled in biosafety level 2 facilities, making high-throughput screening feasible. However, each of these model species have their own limitations.We report and describe the first complete genome sequence of Mycobacterium aurum ATCC23366, an environmental mycobacterium that can also grow in the gut of humans and animals as part of the microbiota. This species shows a comparable resistance profile to that of M. tuberculosis for several anti-TB drugs. The aims of this study were to (i) determine the drug resistance profile of a recently proposed model species, Mycobacterium aurum, strain ATCC23366, for anti-TB drug discovery as well as Mycobacterium smegmatis and Mycobacterium marinum (ii) sequence and annotate the complete genome sequence of this species obtained using Pacific Bioscience technology (iii) perform comparative genomics analyses of the various surrogate strains with M. tuberculosis (iv) discuss how the choice of the surrogate model used for drug screening can affect the drug discovery process.We describe the complete genome sequence of M. aurum, a surrogate model for anti-tuberculosis drug discovery. Most of the genes already reported to be associated with drug resistance are shared between all the surrogate strains and M. tuberculosis. We consider that M. aurum might be used in high-throughput screening for tuberculosis drug discovery. We also highly recommend the use of different model species during the drug discovery screening process.

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July 7, 2019

Trichoderma reesei complete genome sequence, repeat-induced point mutation, and partitioning of CAZyme gene clusters.

Trichoderma reesei (Ascomycota, Pezizomycotina) QM6a is a model fungus for a broad spectrum of physiological phenomena, including plant cell wall degradation, industrial production of enzymes, light responses, conidiation, sexual development, polyketide biosynthesis, and plant-fungal interactions. The genomes of QM6a and its high enzyme-producing mutants have been sequenced by second-generation-sequencing methods and are publicly available from the Joint Genome Institute. While these genome sequences have offered useful information for genomic and transcriptomic studies, their limitations and especially their short read lengths make them poorly suited for some particular biological problems, including assembly, genome-wide determination of chromosome architecture, and genetic modification or engineering.We integrated Pacific Biosciences and Illumina sequencing platforms for the highest-quality genome assembly yet achieved, revealing seven telomere-to-telomere chromosomes (34,922,528 bp; 10877 genes) with 1630 newly predicted genes and >1.5 Mb of new sequences. Most new sequences are located on AT-rich blocks, including 7 centromeres, 14 subtelomeres, and 2329 interspersed AT-rich blocks. The seven QM6a centromeres separately consist of 24 conserved repeats and 37 putative centromere-encoded genes. These findings open up a new perspective for future centromere and chromosome architecture studies. Next, we demonstrate that sexual crossing readily induced cytosine-to-thymine point mutations on both tandem and unlinked duplicated sequences. We also show by bioinformatic analysis that T. reesei has evolved a robust repeat-induced point mutation (RIP) system to accumulate AT-rich sequences, with longer AT-rich blocks having more RIP mutations. The widespread distribution of AT-rich blocks correlates genome-wide partitions with gene clusters, explaining why clustering of genes has been reported to not influence gene expression in T. reesei.Compartmentation of ancestral gene clusters by AT-rich blocks might promote flexibilities that are evolutionarily advantageous in this fungus’ soil habitats and other natural environments. Our analyses, together with the complete genome sequence, provide a better blueprint for biotechnological and industrial applications.

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July 7, 2019

Comparative genomic analysis of Acinetobacter strains isolated from murine colonic crypts.

A restricted set of aerobic bacteria dominated by the Acinetobacter genus was identified in murine intestinal colonic crypts. The vicinity of such bacteria with intestinal stem cells could indicate that they protect the crypt against cytotoxic and genotoxic signals. Genome analyses of these bacteria were performed to better appreciate their biodegradative capacities.Two taxonomically different clusters of Acinetobacter were isolated from murine proximal colonic crypts, one was identified as A. modestus and the other as A. radioresistens. Their identification was performed through biochemical parameters and housekeeping gene sequencing. After selection of one strain of each cluster (A. modestus CM11G and A. radioresistens CM38.2), comparative genomic analysis was performed on whole-genome sequencing data. The antibiotic resistance pattern of these two strains is different, in line with the many genes involved in resistance to heavy metals identified in both genomes. Moreover whereas the operon benABCDE involved in benzoate metabolism is encoded by the two genomes, the operon antABC encoding the anthranilate dioxygenase, and the phenol hydroxylase gene cluster are absent in the A. modestus genomic sequence, indicating that the two strains have different capacities to metabolize xenobiotics. A common feature of the two strains is the presence of a type IV pili system, and the presence of genes encoding proteins pertaining to secretion systems such as Type I and Type II secretion systems.Our comparative genomic analysis revealed that different Acinetobacter isolated from the same biological niche, even if they share a large majority of genes, possess unique features that could play a specific role in the protection of the intestinal crypt.

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July 7, 2019

Whole genome sequence of the heterozygous clinical isolate Candida krusei 81-B-5.

Candida krusei is a diploid, heterozygous yeast that is an opportunistic fungal pathogen in immunocompromised patients. This species also is utilized for fermenting cocoa beans during chocolate production. One major concern in the clinical setting is the innate resistance of this species to the most commonly used antifungal drug fluconazole. Here we report a high-quality genome sequence and assembly for the first clinical isolate of C. krusei, strain 81-B-5, into 11 scaffolds generated with PacBio sequencing technology. Gene annotation and comparative analysis revealed a unique profile of transporters that could play a role in drug resistance or adaptation to different environments. In addition, we show that while 82% of the genome is highly heterozygous, a 2.0 Mb region of the largest scaffold has undergone loss of heterozygosity. This genome will serve as a reference for further genetic studies of this pathogen. Copyright © 2017 Author et al.

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July 7, 2019

Plasmid composition in Aeromonas salmonicida subsp. salmonicida 01-B526 unravels unsuspected type three secretion system loss patterns.

Aeromonas salmonicida subsp. salmonicida is a ubiquitous psychrophilic waterborne bacterium and a fish pathogen. The numerous mobile elements, especially insertion sequences (IS), in its genome promote rearrangements that impact its phenotype. One of the main virulence factors of this bacterium, its type three secretion system (TTSS), is affected by these rearrangements. In Aeromonas salmonicida subsp. salmonicida most of the TTSS genes are encoded in a single locus on a large plasmid called pAsa5, and may be lost when the bacterium is cultivated at a higher temperature (25 °C), producing non-virulent mutants. In a previous study, pAsa5-rearranged strains that lacked the TTSS locus on pAsa5 were produced using parental strains, including 01-B526. Some of the generated deletions were explained by homologous recombination between ISs found on pAsa5, whereas the others remained unresolved. To investigate those rearrangements, short- and long-read high-throughput sequencing technologies were used on the A. salmonicida subsp. salmonicida 01-B526 whole genome.Whole genome sequencing of the 01-B526 strain revealed that its pAsa5 has an additional IS copy, an ISAS5, compared to the reference strain (A449) sequence, which allowed for a previously unknown rearrangement to occur. It also appeared that 01-B526 bears a second large plasmid, named pAsa9, which shares 40 kbp of highly similar sequences with pAsa5. Following these discoveries, previously unexplained deletions were elucidated by genotyping. Furthermore, in one of the derived strains a fusion of pAsa5 and pAsa9, involving the newly discovered ISAS5 copy, was observed.The loss of TTSS and hence virulence is explained by one consistent mechanism: IS-driven homologous recombination. The similarities between pAsa9 and pAsa5 also provide another example of genetic diversity driven by ISs.

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July 7, 2019

Unravelling the complete genome of Archangium gephyra DSM 2261T and evolutionary insights into myxobacterial chitinases.

Family Cystobacteraceae is a group of eubacteria within order Myxococcales and class Deltaproteobacteria that includes more than 20 species belonging to 6 genera, that is, Angiococcus, Archangium, Cystobacter, Hyalangium, Melittangium, and Stigmatella. Earlier these members have been classified based on chitin degrading efficiency such as Cystobacter fuscus and Stigmatella aurantiaca, which are efficient chitin degraders, C. violaceus a partial chitin degrader and Archangium gephyra a chitin nondegrader. Here we report the 12.5 Mbp complete genome of A. gephyra DSM 2261T and compare it with four available genomes within the family Cystobacteraceae. Phylogeny and DNA-DNA hybridization studies reveal that A. gephyra is closest to Angiococcus disciformis, C. violaceus and C. ferrugineus, which are partial chitin degraders of the family Cystobacteraceae. Homology studies reveal the conservation of approximately half of the proteins in these genomes, with about 15% unique proteins in each genome. The total carbohydrate-active enzymes (CAZome) analysis reveals the presence of one GH18 chitinase in the A. gephyra genome whereas eight copies are present in C. fuscus and S. aurantiaca. Evolutionary studies of myxobacterial GH18 chitinases reveal that most of them are likely related to Terrabacteria and Proteobacteria whereas the Archangium GH18 homolog shares maximum similarity with those of chitin nondegrading Acidobacteria.© The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

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July 7, 2019

Complete genome sequence of Leuconostoc suionicum DSM 20241(T) provides insights into its functional and metabolic features.

The genome of Leuconostoc suionicum DSM 20241(T) (=ATCC 9135(T) = LMG 8159(T) = NCIMB 6992(T)) was completely sequenced and its fermentative metabolic pathways were reconstructed to investigate the fermentative properties and metabolites of strain DSM 20241(T) during fermentation. The genome of L. suionicum DSM 20241(T) consists of a circular chromosome (2026.8 Kb) and a circular plasmid (21.9 Kb) with 37.58% G + C content, encoding 997 proteins, 12 rRNAs, and 72 tRNAs. Analysis of the metabolic pathways of L. suionicum DSM 20241(T) revealed that strain DSM 20241(T) performs heterolactic acid fermentation and can metabolize diverse organic compounds including glucose, fructose, galactose, cellobiose, mannose, sucrose, trehalose, arbutin, salcin, xylose, arabinose and ribose.

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July 7, 2019

Draft genome sequence of Streptomyces scabrisporus NF3, an endophyte isolated from Amphipterygium adstringens.

We report the draft genome sequence of Streptomyces scabrisporus NF3, an endophyte isolated from Amphipterygium adstringens in Chiapas, Mexico. This strain produces a new modified linaridin peptide. The genome harbors at least 50 gene clusters for synthases of polyketide and nonribosomal peptides, suggesting a prospective production of various secondary metabolites. Copyright © 2017 Vazquez-Hernandez et al.

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July 7, 2019

Draft nuclear genome sequence of the liquid hydrocarbon–accumulating green microalga Botryococcus braunii race B (Showa).

Botryococcus braunii has long been known as a prodigious producer of liquid hydrocarbon oils that can be converted into combustion engine fuels. This draft genome for the B race of B. braunii will allow researchers to unravel important hydrocarbon biosynthetic pathways and identify possible regulatory networks controlling this unusual metabolism. Copyright © 2017 Browne et al.

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July 7, 2019

Genome-wide analysis of WOX genes in upland cotton and their expression pattern under different stresses.

WUSCHEL-related homeobox (WOX) family members play significant roles in plant growth and development, such as in embryo patterning, stem-cell maintenance, and lateral organ formation. The recently published cotton genome sequences allow us to perform comprehensive genome-wide analysis and characterization of WOX genes in cotton.In this study, we identified 21, 20, and 38 WOX genes in Gossypium arboreum (2n = 26, A2), G. raimondii (2n = 26, D5), and G. hirsutum (2n = 4x = 52, (AD)t), respectively. Sequence logos showed that homeobox domains were significantly conserved among the WOX genes in cotton, Arabidopsis, and rice. A total of 168 genes from three typical monocots and six dicots were naturally divided into three clades, which were further classified into nine sub-clades. A good collinearity was observed in the synteny analysis of the orthologs from At and Dt (t represents tetraploid) sub-genomes. Whole genome duplication (WGD) and segmental duplication within At and Dt sub-genomes played significant roles in the expansion of WOX genes, and segmental duplication mainly generated the WUS clade. Copia and Gypsy were the two major types of transposable elements distributed upstream or downstream of WOX genes. Furthermore, through comparison, we found that the exon/intron pattern was highly conserved between Arabidopsis and cotton, and the homeobox domain loci were also conserved between them. In addition, the expression pattern in different tissues indicated that the duplicated genes in cotton might have acquired new functions as a result of sub-functionalization or neo-functionalization. The expression pattern of WOX genes under different stress treatments showed that the different genes were induced by different stresses.In present work, WOX genes, classified into three clades, were identified in the upland cotton genome. Whole genome and segmental duplication were determined to be the two major impetuses for the expansion of gene numbers during the evolution. Moreover, the expression patterns suggested that the duplicated genes might have experienced a functional divergence. Together, these results shed light on the evolution of the WOX gene family, and would be helpful in future research.

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July 7, 2019

Genome characteristics of Lactobacillus fermentum strain JDFM216 for application as probiotic bacteria.

Lactobacillus fermentum strain JDFM216, isolated from a Korean infant feces sample, possesses the ability to enhance the longevity and immune response of a Caenorhabditis elegans host. To explore the characteristics of strain JDFM216 at the genetic level, we performed whole-genome sequencing using the PacBio system. The circular draft genome has a total length of 2,076,427 bp and a total of 2,682 encoding sequences were identified. Five phylogenetically featured genes possibly related to the longevity and immune response of the host were identified in L. fermentum strain JDFM216. These genes encode UDP-N-acetylglucosamine 1-carboxyvinyltransferase (E.C. 2.5.1.7), ErfK/YbiS/YcfS/YnhG family protein, site-specific recombinase XerD, homocysteine S-methyltransferase (E.C. 2.1.1.10), and aspartate-ammonia ligase (E.C. 6.3.1.1), which are involved in peptidoglycan synthesis and amino acid metabolism in the gut environment. Our findings on the genetic background of L. fermentum strain JDFM216 and its potential candidate genes for host longevity and immune response provide new insight for the application of this strain in the food industry as newly isolated functional probiotic.

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