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July 7, 2019

The genus Brachypodium as a model for perenniality and polyploidy

The genus Brachypodium contains annual and perennial species with both diploid and polyploid genomes. Like the annual species B. distachyon, some of the perennial and polyploid species have traits compatible with use as a model system (e.g. small genomes, rapid generation time, self-fertile and easy to grow). Thus, there is an opportunity to leverage the resources and knowledge developed for B. distachyon to use other Brachypodium species as models for perenniality and the regulation and evolution of polyploid genomes. There are two factors driving an increased interest in perenniality. First, several perennial grasses are being developed as biomass crops for the sustainable production of biofuel and it would be useful to have a perennial model system to rapidly test biotechnological crop improvement strategies for undesirable impacts on perenniality and winter hardiness. In addition, a deeper understanding of the molecular mechanisms underlying perenniality could be used to design strategies for improving energy crops, for example, by changing resource allocation during growth or by altering the onset of dormancy. The second factor driving increased interest in perenniality is the potential environmental benefits of developing perennial grain crops. B. sylvaticum is a perennial with attributes suitable for use as a perennial model system. A high efficiency transformation system has been developed and a genome sequencing project is underway. Since many important crops, including emerging biomass crops, are polyploid, there is a pressing need to understand the rules governing the evolution and regulation of polyploid genomes. Unfortunately, it is difficult to study polyploid crop genomes because of their size and the difficulty of manipulating those plants in the laboratory. By contrast, B. hybridum has a small polyploid genome and is easy to work with in the laboratory. In addition, analysis of the B. hybridum genome, will be greatly aided by the genome sequences of the two extant diploid species (B. distachyon and B. stacei) that apparently gave rise to B. hybridum. Availability of high quality reference genomes for these three species will be a powerful resource for the study of polyploidy.


July 7, 2019

Complete genome sequence of the probiotic bacterium Bifidobacterium breve KCTC 12201BP isolated from a healthy infant.

We present the completely sequenced genome of Bifidobacterium breve CBT BR3, which was isolated from the feces of a healthy infant. The 2.43-Mb genome contains several kinds of genetic factors associated with health promotion of the human host such as oligosaccharide-degrading genes and vitamin-biosynthetic genes. Copyright © 2015. Published by Elsevier B.V.


July 7, 2019

Insights on virulence from the complete genome of Staphylococcus capitis.

Staphylococcus capitis is an opportunistic pathogen of the coagulase negative staphylococci (CoNS). Functional genomic studies of S. capitis have thus far been limited by a lack of available complete genome sequences. Here, we determined the closed S. capitis genome and methylome using Single Molecule Real Time (SMRT) sequencing. The strain, AYP1020, harbors a single circular chromosome of 2.44 Mb encoding 2304 predicted proteins, which is the smallest of all complete staphylococcal genomes sequenced to date. AYP1020 harbors two large mobile genetic elements; a plasmid designated pAYP1020 (59.6 Kb) and a prophage, FAYP1020 (48.5 Kb). Methylome analysis identified significant adenine methylation across the genome involving two distinct methylation motifs (1972 putative 6-methyladenine (m6A) residues identified). Putative adenine methyltransferases were also identified. Comparative analysis of AYP1020 and the closely related CoNS, S. epidermidis RP62a, revealed a host of virulence factors that likely contribute to S. capitis pathogenicity, most notably genes important for biofilm formation and a suite of phenol soluble modulins (PSMs); the expression/production of these factors were corroborated by functional assays. The complete S. capitis genome will aid future studies on the evolution and pathogenesis of the coagulase negative staphylococci.


July 7, 2019

Complete genome of the marine bacterium Wenzhouxiangella marina KCTC 42284(T).

Wenzhouxiangella marina is an obligatory aerobic, Gram-negative, non-motile, rod-shaped bacterium that was isolated from the culture broth of marine microalgae, Picochlorum sp. 122. Here we report the 3.67 MB complete genome (65.26 G+C%) of W. marina KCTC 42284(T) encoding 3,016 protein-coding genes, 43 tRNAs and one rRNA operon. The genomic information supports multiple horizontal gene transfer (HGT) events in the history of W. marina, possibly with other marine bacteria co-existing in marine habitats. Evaluation of genomic signatures revealed 19 such HGT-derived genomic islands. Of these, eight were also supported by “genomic context” that refers to the existence of integrases, transposases and tmRNA genes either inside or in near vicinity to the island. The addition of W. marina genome expands the repertoire of marine bacterial genomic diversity, especially because the strain represents the sole genomic resource of a novel taxonomic family in the bacterial order Chromatiales. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Complete genome sequence of the Clostridium difficile type strain DSM 1296T.

In this study, we sequenced the complete genome of the Clostridium difficile type strain DSM 1296(T). A combination of single-molecule real-time (SMRT) and Illumina sequencing technology revealed the presence of one chromosome and two extrachromosomal elements, the bacteriophage phiCDIF1296T and a putative plasmid-like structure harboring genes of another bacteriophage. Copyright © 2015 Riedel et al.


July 7, 2019

Population genomics reveals additive and replacing horizontal gene transfers in the emerging pathogen Dickeya solani.

Dickeya solani is an emerging pathogen that causes soft rot and blackleg diseases in several crops including Solanum tuberosum, but little is known about its genomic diversity and evolution.We combined Illumina and PacBio technologies to complete the genome sequence of D. solani strain 3337 that was used as a reference to compare with 19 other genomes (including that of the type strain IPO2222(T)) which were generated by Illumina technology. This population genomic analysis highlighted an unexpected variability among D. solani isolates since it led to the characterization of two distinct sub-groups within the D. solani species. This approach also revealed different types of variations such as scattered SNP/InDel variations as well as replacing and additive horizontal gene transfers (HGT). Infra-species (between the two D. solani sub-groups) and inter-species (between D. solani and D. dianthicola) replacing HGTs were observed. Finally, this work pointed that genetic and functional variation in the motility trait could contribute to aggressiveness variability in D. solani.This work revealed that D. solani genomic variability may be caused by SNPs/InDels as well as replacing and additive HGT events, including plasmid acquisition; hence the D. solani genomes are more dynamic than that were previously proposed. This work alerts on precautions in molecular diagnosis of this emerging pathogen.


July 7, 2019

The Brachypodium distachyon reference genome

Grasses provide the bulk of human calories but improvement in grass yields is hindered by the characteristically large and complex genomes of these species; the genomes of wheat, maize, and sugar cane are 17,000, 2300, and 10,000 Mb, respectively. Brachypodium distachyon has one of the smallest genomes of all grasses at 272 Mb, and a number of key traits that make it a good model grass. Brachypodium was the fourth sequenced grass genome, after rice, Sorghum, and maize, and was the first sequenced in the Pooideae subfamily, a diverse group that includes wheat, barley, oat, and rye. The Brachypodium genome was sequenced using a whole genome shotgun approach with Sanger sequencing and is nearly complete with 99.6 % of the sequences anchored to five chromosomes. Sequencing of Brachypodium enabled comparative genomic analysis of grass genomes and shed light on processes involved in chromosome fusions and maintenance of a small genome. The high-quality Brachypodium genome sequence provides a framework for gene expression atlases, resequencing, quantitative trait loci (QTL) mapping, GWAS, and ENCODE datasets. The wealth of Brachypodium genomic resources have cemented its utility as a model organism and will facilitate translational work for improving the grasses that feed the world.


July 7, 2019

Role of restriction-modification systems in prokaryotic evolution and ecology

Restriction–modification (R-M) systems are able to methylate or cleave DNA depending on methylation status of their recognition site. It allows them to protect bacterial cells from invasion by foreign DNA. Comparative analysis of a large number of available bacterial genomes and methylomes clearly demonstrates that the role of R-M systems in bacteria is wider than only defense. R-M systems maintain heterogeneity of a bacterial population and are involved in adaptation of bacteria to change in their environmental conditions. R-M systems can be essential for host colonization by pathogenic bacteria. Phase variation and intragenomic recombinations are sources of the fast evolution of the specificity of R-M systems. This review focuses on the influence of R-M systems on evolution and ecology of prokaryotes.


July 7, 2019

High-quality permanent draft genome sequence of the Lebeckia ambigua-nodulating Burkholderia sp. strain WSM4176.

Burkholderia sp. strain WSM4176 is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from an effective N2-fixing root nodule of Lebeckia ambigua collected in Nieuwoudtville, Western Cape of South Africa, in October 2007. This plant persists in infertile, acidic and deep sandy soils, and is therefore an ideal candidate for a perennial based agriculture system in Western Australia. Here we describe the features of Burkholderia sp. strain WSM4176, which represents a potential inoculant quality strain for L. ambigua, together with sequence and annotation. The 9,065,247 bp high-quality-draft genome is arranged in 13 scaffolds of 65 contigs, contains 8369 protein-coding genes and 128 RNA-only encoding genes, and is part of the GEBA-RNB project proposal (Project ID 882).


July 7, 2019

Genome sequence of Geobacillus thermoglucosidasius DSM2542, a platform hosts for biotechnological applications with industrial potential.

Thermophilic Geobacillus thermoglucosidasius could ferment a wide range of substrates with low nutrient requirements for growth. Here, the first released the complete genome sequence of G. thermoglucosidasius DSM2542 may facilitate the design of rational strategies for further strain improvements and provide information for exploring industrially interesting enzymes with thermotolerant properties. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Complete genome sequence of Bifidobacterium longum KCTC 12200BP, a probiotic strain promoting the intestinal health.

Bifidobacteria constitute a major group of beneficial intestinal bacteria, and are therefore often used to formulate probiotic products in combination with lactic acid bacteria. The availability of bifidobacterial genome sequences has broadened our knowledge on health-promoting factors as well as their safety assessments. Here, we present the complete genome sequence of Bifidobacterium longum CBT BG7 that consists of a 2.45-Mb chromosome and a plasmid. Copyright © 2015. Published by Elsevier B.V.


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