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July 7, 2019

Complete genome sequence of the Arcobacter mytili type strain LMG 24559

Multiple Arcobacter species have been recovered from fresh and con- taminated waters, marine environments, and shellfish. Arcobacter mytili was recov- ered in 2006 from mussels collected from the Ebro River delta in Catalonia, Spain. This study describes the complete whole-genome sequence of the A. mytili type strain LMG 24559 (=F2075T=CECT 7386T).


July 7, 2019

Recombination hotspots in an extended human pseudoautosomal domain predicted from double-strand break maps and characterized by sperm-based crossover analysis.

The human X and Y chromosomes are heteromorphic but share a region of homology at the tips of their short arms, pseudoautosomal region 1 (PAR1), that supports obligate crossover in male meiosis. Although the boundary between pseudoautosomal and sex-specific DNA has traditionally been regarded as conserved among primates, it was recently discovered that the boundary position varies among human males, due to a translocation of ~110 kb from the X to the Y chromosome that creates an extended PAR1 (ePAR). This event has occurred at least twice in human evolution. So far, only limited evidence has been presented to suggest this extension is recombinationally active. Here, we sought direct proof by examining thousands of gametes from each of two ePAR-carrying men, for two subregions chosen on the basis of previously published male X-chromosomal meiotic double-strand break (DSB) maps. Crossover activity comparable to that seen at autosomal hotspots was observed between the X and the ePAR borne on the Y chromosome both at a distal and a proximal site within the 110-kb extension. Other hallmarks of classic recombination hotspots included evidence of transmission distortion and GC-biased gene conversion. We observed good correspondence between the male DSB clusters and historical recombination activity of this region in the X chromosomes of females, as ascertained from linkage disequilibrium analysis; this suggests that this region is similarly primed for crossover in both male and female germlines, although sex-specific differences may also exist. Extensive resequencing and inference of ePAR haplotypes, placed in the framework of the Y phylogeny as ascertained by both Y microsatellites and single nucleotide polymorphisms, allowed us to estimate a minimum rate of crossover over the entire ePAR region of 6-fold greater than genome average, comparable with pedigree estimates of PAR1 activity generally. We conclude ePAR very likely contributes to the critical crossover function of PAR1.


July 7, 2019

Chromosomal Sil system contributes to silver resistance in E. coli ATCC 8739.

The rise of antibiotic resistance in pathogenic bacteria is endangering the efficacy of antibiotics, which consequently results in greater use of silver as a biocide. Chromosomal mapping of the Cus system or plasmid encoded Sil system and their relationship with silver resistance was studied for several gram-negative bacteria. However, only few reports investigated silver detoxification mediated by the Sil system integrated in Escherichia coli chromosome. Accordingly, this work aimed to study the Sil system in E. coli ATCC 8739 and to produce evidence for its role in silver resistance development. Silver resistance was induced in E. coli ATCC 8739 by stepwise passage in culture media containing increasing concentrations of AgNO3. The published genome of E. coli ATCC 8739 contains a region showing strong homology to the Sil system genes. The role of this region in E. coli ATCC 8739 was assessed by monitoring the expression of silC upon silver stress, which resulted in a 350-fold increased expression. De novo sequencing of the whole genome of a silver resistant strain derived from E. coli ATCC 8739 revealed mutations in ORFs putative for SilR and CusR. The silver resistant strain (E. coli AgNO3R) showed constitutive expression of silC which posed a cost of fitness resulting in retarded growth. Furthermore, E. coli AgNO3R exhibited cross-resistance to ciprofloxacin and a slightly increased tolerance to ampicillin. This study demonstrates that E. coli is able to develop resistance to silver, which may pose a threat towards an effective use of silver compounds as antiseptics.


July 7, 2019

Mitochondrial genomes of two diplectanids (Platyhelminthes: Monogenea) expose paraphyly of the order Dactylogyridea and extensive tRNA gene rearrangements.

Recent mitochondrial phylogenomics studies have reported a sister-group relationship of the orders Capsalidea and Dactylogyridea, which is inconsistent with previous morphology- and molecular-based phylogenies. As Dactylogyridea mitochondrial genomes (mitogenomes) are currently represented by only one family, to improve the phylogenetic resolution, we sequenced and characterized two dactylogyridean parasites, Lamellodiscus spari and Lepidotrema longipenis, belonging to a non-represented family Diplectanidae.The L. longipenis mitogenome (15,433 bp) contains the standard 36 flatworm mitochondrial genes (atp8 is absent), whereas we failed to detect trnS1, trnC and trnG in L. spari (14,614 bp). Both mitogenomes exhibit unique gene orders (among the Monogenea), with a number of tRNA rearrangements. Both long non-coding regions contain a number of different (partially overlapping) repeat sequences. Intriguingly, these include putative tRNA pseudogenes in a tandem array (17 trnV pseudogenes in L. longipenis, 13 trnY pseudogenes in L. spari). Combined nucleotide diversity, non-synonymous/synonymous substitutions ratio and average sequence identity analyses consistently showed that nad2, nad5 and nad4 were the most variable PCGs, whereas cox1, cox2 and cytb were the most conserved. Phylogenomic analysis showed that the newly sequenced species of the family Diplectanidae formed a sister-group with the Dactylogyridae + Capsalidae clade. Thus Dactylogyridea (represented by the Diplectanidae and Dactylogyridae) was rendered paraphyletic (with high statistical support) by the nested Capsalidea (represented by the Capsalidae) clade.Our results show that nad2, nad5 and nad4 (fast-evolving) would be better candidates than cox1 (slow-evolving) for species identification and population genetics studies in the Diplectanidae. The unique gene order pattern further suggests discontinuous evolution of mitogenomic gene order arrangement in the Class Monogenea. This first report of paraphyly of the Dactylogyridea highlights the need to generate more molecular data for monogenean parasites, in order to be able to clarify their relationships using large datasets, as single-gene markers appear to provide a phylogenetic resolution which is too low for the task.


July 7, 2019

Genomic insights into date palm origins.

With the development of next-generation sequencing technology, the amount of date palm (Phoenix dactylifera L.) genomic data has grown rapidly and yielded new insights into this species and its origins. Here, we review advances in understanding of the evolutionary history of the date palm, with a particular emphasis on what has been learned from the analysis of genomic data. We first record current genomic resources available for date palm including genome assemblies and resequencing data. We discuss new insights into its domestication and diversification history based on these improved genomic resources. We further report recent discoveries such as the existence of wild ancestral populations in remote locations of Oman and high differentiation between African and Middle Eastern populations. While genomic data are consistent with the view that domestication took place in the Gulf region, they suggest that the process was more complex involving multiple gene pools and possibly a secondary domestication. Many questions remain unanswered, especially regarding the genetic architecture of domestication and diversification. We provide a road map to future studies that will further clarify the domestication history of this iconic crop.


July 7, 2019

Salicibibacter kimchii gen. nov., sp. nov., a moderately halophilic and alkalitolerant bacterium in the family Bacillaceae, isolated from kimchi.

A moderately halophilic and alkalitolerant bacterial strain NKC1-1T was isolated from commercial kimchi in Korea. Strain NKC1-1T was Gram-stain-positive, aerobic, rod-shaped, non-motile, and contained diaminopimelic acid-type murein. Cell growth was observed in a medium containing 0-25% (w/v) NaCl (optimal at 10% [w/v]), at 20-40°C (optimal at 37°C) and pH 6.5-10.0 (optimal at pH 9.0). The major isoprenoid quinone of the isolate was menaquinone-7, and the major polar lipids were phosphatidylglycerol and unidentified phospholipids. Cell membrane of the strain contained iso-C17:0 and anteiso-C15:0 as the major fatty acids. Its DNA G + C content was 45.2 mol%. Phylogenetic analysis indicated the strain to be most closely related to Geomicrobium halophilum with 92.7-92.9% 16S rRNA gene sequence similarity. Based on polyphasic taxonomic evaluation with phenotypic, phylogenetic, and chemotaxonomic analyses, the strain represents a novel species in a new genus, for which the name Salicibibacter kimchii gen. nov., sp. nov. is proposed (= CECT 9537T; KCCM 43276T).


July 7, 2019

Identification and genome analysis of Deinococcus actinosclerus SJTR1, a novel 17ß-estradiol degradation bacterium.

Biodegradation with microorganisms is considered as an efficient strategy to remove the environmental pollutants. In this work, Deinococcus actinosclerus SJTR1 isolated from the wastewater was confirmed with great degradation capability to 17ß-estradiol, one typical estrogen chemical. It could degrade nearly 90% of 17ß-estradiol (10 mg/L) in 5 days and transform it into estrone; its degradation kinetics fitted for the first-order kinetic equation. The whole genome sequence of D. actinosclerus SJTR1 was obtained and annotated, containing one chromosome (3,315,586 bp) and four plasmids (ranging from 17,267 bp to 460,244 bp). A total of 3913 CDSs and 73 RNA genes (including 12 rRNA genes, 50 tRNA genes, and 11 ncRNA genes) were identified in its whole genome sequence. On this basis, a series of potential genes involved in steroid metabolism and stress responses of D. actinosclerus SJTR1 were predicted. It is the first report of Deinococcus strain with the degradation capability to estrogens. This work could enrich the genome sources of the estrogen-degrading strains and promote the degradation mechanism study of 17ß-estradiol in bacteria.


July 7, 2019

Complete genome sequence of Bordetella sp. HZ20 sheds light on the ecological role of bacterium without algal-polysaccharides degrading abilities in the brown seaweed-abundant environment

Bordetella sp. HZ20 was isolated from the surface of brown seaweed (Laminaria japonica) and absence of the abilities to decompose the brown seaweed. The genome of Bordetella sp. HZ20 was sequenced and comprised of one circular chromosome with the size of 4,227,194?bp and DNA G?+?C content of 55.5%. Genomic annotation showed that, Bordetella sp. HZ20 may have chitin degradation related enzymes, heparin-sulfate lyase-like protein and enzymes related to the synthase and utilization of polyhydroxyalkanoate for carbon utilization, nitrate and nitrite reductase, glutamate dehydrogenase, glutamate synthase and glutamine synthetase for nitrogen cycle, polyphosphate kinases (pkk1 and pkk2), the high-affinity phosphate-specific transport (Pst) system and the low-affinity inorganic phosphate transporter (pitA) for phosphorus cycle, cysteine synthase and type III acyl coenzyme A transferase (dddD) for sulfur cycle. These features indicated the metabolic patterns of Bordetella sp. HZ20 in C, N, P and S cycles. In addition, the predicted Pst system and cysteine synthase were also related to biofilm formation which showed the potential pathogenicity of Bordetella sp. HZ20 to the cells of animals or plants. This study provides evidences about the metabolic patterns of Bordetella sp. HZ20 and broadens our understandings about ecological roles of bacterium without algal-polysaccharides degrading abilities in the brown seaweed-abundant environment.


July 7, 2019

Lifestyle of Lactobacillus hordei isolated from water kefir based on genomic, proteomic and physiological characterization.

Water kefir is a traditional fermented beverage made from sucrose, water, kefir granules, dried or fresh fruits. In our water kefir granules, Lactobacillus (L.) hordei is one of the predominant lactic acid bacteria (LAB) species of this presumed symbiotic consortium. It faces abundant sucrose versus limitation of amino- and fatty acids in an acidic environment. Sequencing of the genome of L. hordei TMW 1.1822 revealed one chromosome plus three plasmids. The size of the chromosome was 2.42?Mbp with a GC content of 35% GC and 2461 predicted coding sequences. Furthermore, we identified 1474 proteins upon growth on water kefir medium. Metabolic prediction revealed all enzymes required for the glycolytic Embden-Meyerhof (EMP) and phosphoketolase (PKP) pathways. Genes encoding all enzymes involved in citrate, pyruvate and mannitol metabolism are present. Moreover, it was confirmed that L. hordei is prototrophic for 11 amino acids and auxotrophic for 6 amino acids when combining putative biosynthesis pathways for amino acids with physiological characterization. Still, for glycine, serine and methionine no sure auxotype could be determined. The OppABCDF peptide transport system is complete, and 13 genes encoding peptidases are present. The arginine deiminase system, was predicted to be complete except for carbamate kinase, thus enabling neutralization reactions via ammonium formation but no additional energy generation. Taken together our findings enable prediction of the L. hordei lifestyle in water kefir: Abundant sucrose is consumed directly via parallel EMP and PK pathways and is also extracellularly converted to dextran and fructose by a glucansucrase, leaving fructose as additional carbon source. Essential amino acids (in the form of peptides) and citrate are acquired from fruits. In the lack of FabB unsaturated fatty acids are synthesized by predicted alternative enzymes. Formation of acetoin and diacetyl as well as arginine conversion reactions enable acidification limitation. Other members of the water kefir consortium (yeasts, acetic acid bacteria) likely facilitate or support growth of L. hordei by delivering gluconate, mannitol, amino- and fatty acids and vitamins. Copyright © 2018 Elsevier B.V. All rights reserved.


July 7, 2019

Whole-genome sequence of purple non-sulfur bacteria, Rhodobacter sphaeroides strain MBTLJ-8 with improved CO2 reduction capacity.

Rhodobacter sphaeroides consists of two chromosomes and many plasmids and incorporates many environmentally important functional gene. Rhodobacter sphaeroides MBTLJ-8 was derived from R. sphaeroides 2.4.1 using chemical mutagenesis and is characterized by enhanced production of physiological active compounds as well as improved carbon dioxide reduction capacity. We reported the complete genome sequence and characteristics based on genomic information of this bacteria. Therefore, this genome sequence provides elucidation for improved CO2 fixation and enhanced physiological active compounds production, and will be used as the efficient photosynthetic bacteria for the biological CO2 reduction system. Copyright © 2018 Elsevier B.V. All rights reserved.


July 7, 2019

Draft genome sequence of the xanthocidin-producing strain Streptomyces sp. AcE210, isolated from a root nodule of Alnus glutinosa (L.).

Streptomyces sp. strain AcE210 exhibited antibacterial activity toward Gram-positive microorganisms and turned out to be a rare producer of the special- ized metabolite xanthocidin. The 10.6-Mb draft genome sequence gives insight into the complete specialized metabolite production capacity and builds the basis to find and locate the biosynthetic gene cluster of xanthocidin.


July 7, 2019

Genome analysis of Rhodococcus Sp. DSSKP-R-001: A highly effective ß-estradiol-degrading bacterium.

We screened bacteria that use E2 as its sole source of carbon and energy for growth and identified them as Rhodococcus, and we named them DSSKP-R-001. For a better understanding of the metabolic potential of the strain, whole genome sequencing of Rhodococcus DSSKP-R-001 and annotation of the functional genes were performed. The genomic sketches included a predicted protein-coding gene of approximately 5.4?Mbp with G?+?C content of 68.72% and 5180. The genome of Rhodococcus strain DSSKP-R-001 consists of three replicons: one chromosome and two plasmids of 5.2, 0.09, and 0.09, respectively. The results showed that there were ten steroid-degrading enzymes distributed in the whole genome of the strain. The existence and expression of estradiol-degrading enzymes were verified by PCR and RTPCR. Finally, comparative genomics was used to compare multiple strains of Rhodococcus. It was found that Rhodococcus DSSKP-R-001 had the highest similarity to Rhodococcus sp. P14 and there were 2070 core genes shared with Rhodococcus sp. P14, Rhodococcus jostii RHA1, Rhodococcus opacus B4, and Rhodococcus equi 103S, showing evolutionary homology. In summary, this study provides a comprehensive understanding of the role of Rhodococcus DSSKP-R-001 in estradiol-efficient degradation of these assays for Rhodococcus. DSSKP-R-001 in bioremediation and evolution within Rhodococcus has important meaning.


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