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July 7, 2019

Integrating mass spectrometry and genomics for cyanobacterial metabolite discovery.

Filamentous marine cyanobacteria produce bioactive natural products with both potential therapeutic value and capacity to be harmful to human health. Genome sequencing has revealed that cyanobacteria have the capacity to produce many more secondary metabolites than have been characterized. The biosynthetic pathways that encode cyanobacterial natural products are mostly uncharacterized, and lack of cyanobacterial genetic tools has largely prevented their heterologous expression. Hence, a combination of cutting edge and traditional techniques has been required to elucidate their secondary metabolite biosynthetic pathways. Here, we review the discovery and refined biochemical understanding of the olefin synthase and fatty acid ACP reductase/aldehyde deformylating oxygenase pathways to hydrocarbons, and the curacin A, jamaicamide A, lyngbyabellin, columbamide, and a trans-acyltransferase macrolactone pathway encoding phormidolide. We integrate into this discussion the use of genomics, mass spectrometric networking, biochemical characterization, and isolation and structure elucidation techniques.


July 7, 2019

Assembly and characterization of the MHC class I region of the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis).

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis; YFP) is the sole freshwater subspecies of N. asiaeorientalis and is now critically endangered. Major histocompatibility complex (MHC) is a family of highly polymorphic genes that play an important immunological role in antigen presentation in the vertebrates. Currently, however, little is known about MHC region in the genome of the YFP, which hampers conservation genetics and evolutionary ecology study using MHC genes. In this work, a nucleotide sequence of 774,811 bp covering the YFP MHC class I region was obtained by screening a YFP bacterial artificial chromosome (BAC) library, followed by sequencing and assembly of positive BAC clones. A total of 45 genes were successfully annotated, of which four were MHC class I genes. There are high similarities among the four YFP MHC class I genes (>94 %). Divergence in the coding region of the four YFP MHC class I genes is mainly localized to exons 2 and 3, which encode the antigen-binding sites of MHC class I genes. Additionally, comparison of the MHC structure in YFP to those of cattle, sheep, and pig showed that MHC class I genes are located in genome regions with regard to the conserved genes, and the YFP contains the fewest MHC class I genes among these species. This is the first report characterizing a cetacean MHC class I region and describing its organization, which would be valuable for further investigation of adaptation in natural populations of the YFP and other cetaceans.


July 7, 2019

rHAT: fast alignment of noisy long reads with regional hashing.

Single Molecule Real-Time (SMRT) sequencing has been widely applied in cutting-edge genomic studies. However, it is still an expensive task to align the noisy long SMRT reads to reference genome by state-of-the-art aligners, which is becoming a bot-tleneck in applications with SMRT sequencing. Novel approach is on demand for improving the efficiency and effectiveness of SMRT read alignment.We propose Regional Hashing-based Alignment Tool (rHAT), a seed-and-extension-based read alignment approach specifically designed for noisy long reads. rHAT indexes reference genome by regional hash table (RHT), a hash table-based index which describes the short tokens within local windows of reference genome. In the seeding phase, rHAT utilizes RHT for efficiently calculating the occurrences of short token matches between partial read and local genomic windows to find highly possible candidate sites. In the extension phase, a sparse dynamic programming-based heuristic approach is used for reducing the cost of aligning read to the candidate sites. By benchmarking on the real and simulated datasets from various prokaryote and eukaryote genomes, we demonstrated that rHAT can effectively align SMRT reads with outstanding throughput. rHAT is implemented in C++; the source code is available at https://github.com/derekguan/rHAT CONTACT: ydwang@hit.edu.cn. © The Author (2015). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.


July 7, 2019

Complete genome sequence of deoxynivalenol-degrading bacterium Devosia sp. strain A16.

The strain A16, capable of degrading deoxynivalenol was isolated from a wheat field and identified preliminarily as Devosia sp. Here, we present the genome sequence of the Devosia sp. A16, which has a size of 5,032,994bp, with 4913 coding sequences (CDSs). The annotated full genome sequence of the Devosia sp. A16 strain might shed light on the function of its degradation. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Complete genome sequence of the Variibacter gotjawalensis GJW-30(T) from soil of lava forest, Gotjawal.

Variibacter gotjawalensis GJW-30(T) is a gram-negative, strictly aerobic bacterium to form pleomorphic. Here we present the 4.5-Mb genome sequence of the type strain of V. gotjawalensis GJW-30(T), which consists a chromosome for the total 4,586,237bp with a G+C content of 62.2mol%. This is the first report of the full genome sequence of a species of the novel genus Variibacter isolated from Gotjawal, a unique area in Jeju, Republic of Korea. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Complete genome of Pseudoalteromonas phenolica KCTC 12086(T) (= O-BC30(T)), a marine bacterium producing polybrominated aromatic compounds.

Pseudoalteromonas phenolica is a Gram-negative, rod-shaped, flagellated, aerobic, antibiotic-producing bacterium that was isolated from seawater off Ogasawara Island, Japan. Here, we report the complete genome of P. phenolica KCTC 12086(T) (= O-BC30(T)), which consists of 4,868,993 bp (G+C content of 40.6%) with two chromosomes, 4168 protein-coding genes, 113 tRNAs and 9 rRNA operons. In addition, several genes related to phenolic anti-methicillin-resistant Staphylococcus aureus substances were detected in the genome suggesting that biosynthesis of industrially important polybrominated aromatic compounds could be better understood with the availability of genome data of P. phenolica. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

hybridSPAdes: an algorithm for hybrid assembly of short and long reads.

Recent advances in single molecule real-time (SMRT) and nanopore sequencing technologies have enabled high-quality assemblies from long and inaccurate reads. However, these approaches require high coverage by long reads and remain expensive. On the other hand, the inexpensive short reads technologies produce accurate but fragmented assemblies. Thus, a hybrid approach that assembles long reads (with low coverage) and short reads has a potential to generate high-quality assemblies at reduced cost.We describe hybridSPAdes algorithm for assembling short and long reads and benchmark it on a variety of bacterial assembly projects. Our results demonstrate that hybridSPAdes generates accurate assemblies (even in projects with relatively low coverage by long reads) thus reducing the overall cost of genome sequencing. We further present the first complete assembly of a genome from single cells using SMRT reads.hybridSPAdes is implemented in C++?as a part of SPAdes genome assembler and is publicly available at http://bioinf.spbau.ru/en/spades CONTACT: d.antipov@spbu.ruSupplementary information: supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.


July 7, 2019

Complete genome sequence of Celeribacter marinus IMCC12053(T), the host strain of marine bacteriophage P12053L.

Isolated from coastal seawater from Yellow Sea of Korea, Celeribacter marinus IMCC12053 was used as the host bacterium for bacteriophage P12053L. Here we report the complete genome sequence of strain IMCC12053 for further study of the marine bacteriophage P12053L functional genes. Single molecule real-time technology (PacBio RSII) was used for the single circular chromosome that is 3,096,705 base pairs in length and the GC content is 56.24%. It contains 3155 ORFs with 45 tRNAs and 6 rRNAs genes. N(6)-methyladenosine patterns were also investigated for 32 unmethylated genes and intergenic regions that covered many regulators and phage genes as well as ribosomal RNA genes and tRNA genes. Cryptic N(4)-methylcytosine pattern was investigated to speculate GpC methylase activity throughout the genome. Comparative genomics with other Celeribacter genomes were carried out for polyaromatic hydrocarbon degradation, but there were no aromatic ring oxygenases in IMCC12053 when compared to Celeribacter indicus P73. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Complete genome sequence of Agarivorans gilvus WH0801(T), an agarase-producing bacterium isolated from seaweed.

Agarivorans gilvus WH0801(T), an agarase-producing bacterium, was isolated from the surface of seaweed. Here, we present the complete genome sequence, which consists of one circular chromosome of 4,416,600bp with a GC content of 45.9%. This genetic information will provide insight into biotechnological applications of producing agar for food and industry. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

OxyR-dependent formation of DNA methylation patterns in OpvABOFF and OpvABON cell lineages of Salmonella enterica.

Phase variation of the Salmonella enterica opvAB operon generates a bacterial lineage with standard lipopolysaccharide structure (OpvAB(OFF)) and a lineage with shorter O-antigen chains (OpvAB(ON)). Regulation of OpvAB lineage formation is transcriptional, and is controlled by the LysR-type factor OxyR and by DNA adenine methylation. The opvAB regulatory region contains four sites for OxyR binding (OBSA-D), and four methylatable GATC motifs (GATC1-4). OpvAB(OFF) and OpvAB(ON) cell lineages display opposite DNA methylation patterns in the opvAB regulatory region: (i) in the OpvAB(OFF) state, GATC1 and GATC3 are non-methylated, whereas GATC2 and GATC4 are methylated; (ii) in the OpvAB(ON) state, GATC2 and GATC4 are non-methylated, whereas GATC1 and GATC3 are methylated. We provide evidence that such DNA methylation patterns are generated by OxyR binding. The higher stability of the OpvAB(OFF) lineage may be caused by binding of OxyR to sites that are identical to the consensus (OBSA and OBSc), while the sites bound by OxyR in OpvAB(ON) cells (OBSB and OBSD) are not. In support of this view, amelioration of either OBSB or OBSD locks the system in the ON state. We also show that the GATC-binding protein SeqA and the nucleoid protein HU are ancillary factors in opvAB control.© The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.


July 7, 2019

Long read and single molecule DNA sequencing simplifies genome assembly and TAL effector gene analysis of Xanthomonas translucens.

The species Xanthomonas translucens encompasses a complex of bacterial strains that cause diseases and yield loss on grass species including important cereal crops. Three pathovars, X. translucens pv. undulosa, X. translucens pv. translucens and X. translucens pv.cerealis, have been described as pathogens of wheat, barley, and oats. However, no complete genome sequence for a strain of this complex is currently available.A complete genome sequence of X. translucens pv. undulosa strain XT4699 was obtained by using PacBio long read, single molecule, real time (SMRT) DNA sequences and Illumina sequences. Draft genome sequences of nineteen additional X. translucens strains, which were collected from wheat or barley in different regions and at different times, were generated by Illumina sequencing. Phylogenetic relationships among different Xanthomonas strains indicates that X. translucens are members of a distinct clade from so-called group 2 xanthomonads and three pathovars of this species, undulosa, translucens and cerealis, represent distinct subclades in the group 1 clade. Knockout mutation of type III secretion system of XT4699 eliminated the ability to cause water-soaking symptoms on wheat and barley and resulted in a reduction in populations on wheat in comparison to the wild type strain. Sequence comparison of X. translucens strains revealed the genetic variation on type III effector repertories among different pathovars or within one pathovar. The full genome sequence of XT4699 reveals the presence of eight members of the Transcription-Activator Like (TAL) effector genes, which are phylogenetically distant from previous known TAL effector genes of group 2 xanthomonads. Microarray and qRT-PCR analyses revealed TAL effector-specific wheat gene expression modulation.PacBio long read sequencing facilitates the assembly of Xanthomonas genomes and the multiple TAL effector genes, which are difficult to assemble from short read platforms. The complete genome sequence of X. translucens pv. undulosa strain XT4699 and draft genome sequences of nineteen additional X. translucens strains provides a resource for further genetic analyses of pathogenic diversity and host range of the X. translucens species complex. TAL effectors of XT4699 strain play roles in modulating wheat host gene expressions.


July 7, 2019

Complete genome of brown algal polysaccharides-degrading Pseudoalteromonas issachenkonii KCTC 12958(T) (=KMM 3549(T)).

Pseudoalteromonas issachenkonii is a Gram-negative, rod-shaped, flagellated, aerobic, chemoorganotrophic marine bacterium that was isolated from the thallus of Fucus evanescens (marine brown macroalgae) sampled from the Kraternaya Bight of the Kurile Islands in the Pacific Ocean. Here, we report the complete genome of P. issachenkonii KCTC 12958(T) (=KMM 3549(T)=LMG 19697(T)=CIP 106858(T)), which consists of 4,131,541bp (G+C content of 40.3%) with two chromosomes, 3538 protein-coding genes, 102 tRNAs and 8 rRNA operons. Several genes related to glycoside hydrolases, proteases, and bacteriolytic- and hemolytic activities were detected in the genome that help explain how the strain mediates degradation of algal cell wall and decomposes algal polysaccharides into industrially applicable products. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Oral phage therapy of acute bacterial diarrhea with two coliphage preparations: A randomized trial in children from Bangladesh

Background Antibiotic resistance is rising in important bacterial pathogens. Phage therapy (PT), the use of bacterial viruses infecting the pathogen in a species-specific way, is a potential alternative. Method T4-like coliphages or a commercial Russian coliphage product or placebo was orally given over 4 days to Bangladeshi children hospitalized with acute bacterial diarrhea. Safety of oral phage was assessed clinically and by functional tests; coliphage and Escherichia coli titers and enteropathogens were determined in stool and quantitative diarrhea parameters (stool output, stool frequency) were measured. Stool microbiota was studied by 16S rRNA gene sequencing; the genomes of four fecal Streptococcus isolates were sequenced. Findings No adverse events attributable to oral phage application were observed (primary safety outcome). Fecal coliphage was increased in treated over control children, but the titers did not show substantial intestinal phage replication (secondary microbiology outcome). 60% of the children suffered from a microbiologically proven E. coli diarrhea; the most frequent diagnosis was ETEC infections. Bacterial co-pathogens were also detected. Half of the patients contained phage-susceptible E. coli colonies in the stool. E. coli represented less than 5% of fecal bacteria. Stool ETEC titers showed only a short-lived peak and were otherwise close to the replication threshold determined for T4 phage in vitro. An interim analysis after the enrollment of 120 patients showed no amelioration in quantitative diarrhea parameter by PT over standard care (tertiary clinical outcome). Stool microbiota was characterized by an overgrowth with Streptococcus belonging to the Streptococcus gallolyticus and Streptococcus salivarius species groups, their abundance correlated with quantitative diarrhea outcome, but genome sequencing did not identify virulence genes. Interpretation Oral coliphages showed a safe gut transit in children, but failed to achieve intestinal amplification and to improve diarrhea outcome, possibly due to insufficient phage coverage and too low E. coli pathogen titers requiring higher oral phage doses. More knowledge is needed on in vivo phage–bacterium interaction and the role of E. coli in childhood diarrhea for successful PT. Funding The study was supported by a grant from Nestlé Nutrition and Nestlé Health Science. The trial was registered with Identifier NCT00937274 at ClinicalTrials.gov.


July 7, 2019

Complete genome sequence of Staphylococcus equorum KS1039 isolated from Saeu-jeotgal, Korean high-salt-fermented seafood.

Staphylococcus equorum KS1039 was isolated from a form of traditional Korean high-salt-fermented seafood called Saeu-jeotgal, and exhibited growth at a NaCl (w/v) concentration of 25%. Comparative genome analyses with two other strains revealed the presence of two potassium voltage-gated channel genes uniquely in KS1039, which might be involved in salt tolerance. This first complete genome sequence of the species will increase our understanding of the genetic factors allowing it to be safely consumed by humans and to inhabit high-salt environments. Copyright © 2015 Elsevier B.V. All rights reserved.


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