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July 7, 2019

Complete genome sequence of Planococcus donghaensis JH1(T), a pectin-degrading bacterium.

The type strain Planococcus donghaensis JH1(T) is a psychrotolerant and halotolerant bacterium with starch-degrading ability. Here, we determine the carbon utilization profile of P. donghaensis JH1(T) and report the first complete genome of the strain. This study revealed the strain’s ability to utilize pectin and d-galacturonic acid, and identified genes responsible for degradation of the polysaccharides. The genomic information provided may serve as a fundamental resource for full exploration of the biotechnological potential of P. donghaensis JH1(T). Copyright © 2017. Published by Elsevier B.V.


July 7, 2019

Assessment of bacterial profiles in aged, home-made Sichuan paocai brine with varying titratable acidity by PacBio SMRT Sequencing technology

Sichuan paocai, a traditional Chinese fermented vegetable, is rife with lactic acid bacteria (LAB). However, the precise bacterial profiles of home-made Sichuan paocai brine (HSPB) remain unclear. In this study, the bacterial compositions of 38 aged HSPB samples with varying titratable acidity (TA) were determined by SMRT sequencing of the full-length 16S rRNA gene. The lactic and acetic acids of HSPBs were also measured to determine any relevance with the bacterial profiles. The SMRT sequencing results reveal that the HSPB bacterial communities were comprised of numerous phylogenetic taxa, including 35 phyla, 371 genera, and 593 species; the bacterial diversity decreased as HSPB acidity increased. Lactobacillus acetotolerans, which was positively correlated to HSPB acidity, was the most dominant species followed by Lactobacillus brevis, which was positively related to acetic acid in the samples. A few opportunistic pathogens (e.g. Serratia marcescens and Stenotrophomonas maltophilia) were also detected. Sample groups with lower acidity had higher bacterial diversity and more Lactobacillus species with relative abundance >1% and opportunistics than higher-acidity samples. The results presented here report the comprehensive bacterial profiles of home-made Sichuan paocai for the first time via SMRT sequencing technology and the correlation between TA and bacterial compositions. It is necessary to further investigate the opportunistics detected in this work as they relate to the safety and quality of paocai.


July 7, 2019

Complete genome sequence of the drought resistance-promoting endophyte Klebsiella sp. LTGPAF-6F.

Bacterial endophytes with capacity to promote plant growth and improve plant tolerance against biotic and abiotic stresses have importance in agricultural practice and phytoremediation. A plant growth-promoting endophyte named Klebsiella sp. LTGPAF-6F, which was isolated from the roots of the desert plant Alhagi sparsifolia in north-west China, exhibits the ability to enhance the growth of wheat under drought stress. The complete genome sequence of this strain consists of one circular chromosome and two circular plasmids. From the genome, we identified genes related to the plant growth promotion and stress tolerance, such as nitrogen fixation, production of indole-3-acetic acid, acetoin, 2,3-butanediol, spermidine and trehalose. This genome sequence provides a basis for understanding the beneficial interactions between LTGPAF-6F and host plants, and will facilitate its applications as biotechnological agents in agriculture. Copyright © 2017 Elsevier B.V. All rights reserved.


July 7, 2019

Investigation of compatible solutes synthesis and transport of Virgibacillus halodenitrificans PDB-F2 with complete genome analysis

The salt-tolerant mechanism of compatible solutes in the different microorganisms is always a research hotspot, which can help us understand how organism endures the salty environment. Virgibacillus halodenitrificans PDB-F2 could survive in high salinity and degrade phenol, which is a good candidate for wastewater treatment. This study investigated the salt-tolerant mechanism of compatible solutes of this strain and got an insight into its genetic basis through genome sequencing and analyzing. The results found that Virgibacillus halodenitrificans PDB-F2 endured 12% (w/v) NaCl condition by synthesizing or uptaking ectoine, hydroxyectoine, trehalose, glutamic acid and betaine. Osmoprotective effects of exogenous compatible solutes on this strain were hydroxyectoine > ectoine > L-proline > trehalose > glutamate acid > betaine. Under osmotic shock, the strain had a higher preference for hydroxyectoine than ectoine, and the ectoine transport was stimulated at both levels of transport activity and transcription. The sequencing and analyzing of strain genome showed that this strain contained a circular chromosome (3,869,935 bp) and one plasmid (47,824 bp), revealing the genes related with synthesis and transport of above compatible solutes. This study provided further information on the understanding of salt-tolerant mechanism of Virgibacillus halodenitrificans PDB-F2 by compatible solutes.


July 7, 2019

Complete genome sequence of a natural compounds producer, Streptomyces violaceus S21.

The complete genome sequence of Streptomyces violaceus strain S21, a valuable natural compounds producer isolated from the forest soil, is firstly presented here. The genome comprised 7.91M bp, with a G + C content of 72.65%. A range of genes involved in pathways of secondary product biosynthesis were predicted. The genome sequence is available at DDBJ/EMBL/Genbank under the accession number CP020570. This genome is annotated with 6856 predicted genes identifying the natural product biosynthetic gene clusters in S. violaceus.


July 7, 2019

Whole genome characterization of a naturally occurring vancomycin-dependent Enterococcus faecium from a patient with bacteremia.

Vancomycin-dependent enterococci are a relatively uncommon phenotype recovered in the clinical laboratory. Recognition and recovery of these isolates are important, to provide accurate identification and susceptibility information to treating physicians. Herein, we describe the recovery of a vancomycin-dependent and revertant E. faecium isolates harboring vanB operon from a patient with bacteremia. Using whole genome sequencing, we found a unique single nucleotide polymorphism (S186N) in the D-Ala-D-Ala ligase (ddl) conferring vancomycin-dependency. Additionally, we found that a majority of in vitro revertants mutated outside ddl, with some strains harboring mutations in vanS, while others likely containing novel mechanisms of reversion. Copyright © 2017 Elsevier B.V. All rights reserved.


July 7, 2019

Plasmid dynamics in Vibrio parahaemolyticus strains related to shrimp Acute Hepatopancreatic Necrosis Syndrome (AHPNS).

Vibrio parahaemolyticus is a causative agent of acute hapatopancreatic necrosis syndrome (AHPNS) which causes early mortality in white shrimp. Emergence of AHPNS has caused tremendous economic loss for aquaculture industry particularly in Asia since 2010. Previous studies reported that strains causing AHPNS harbor a 69-kb plasmid with possession of virulence genes, pirA and pirB. However, genetic variation of the 69-kb plasmid among AHPNS related strains has not been investigated. This study aimed to analyze genetic composition and diversity of the 69-kb plasmid in strains isolated from shrimps affected by AHPNS. Plasmids recovered from V. parahaemolyticus strain VPE61 which represented typical AHPNS pathogenicity, strain VP2HP which did not represent AHPNS pathogenicity but was isolated from AHPNS affected shrimp and other AHPNS V. parahaemolyticus isolates in Genbank were investigated. Protein coding genes of the 69-kb plasmid from the strain VPE61 were identical to that of AHPNS strain from Vietnam except the inverted complement 3.4-kb transposon covering pirA and pirB. The strain VP2HP possessed remarkable large 183-kb plasmid which shared similar protein coding genes to those of the 69-kb plasmid from strain VPE61. However, the 3.4-kb transposon covering pirA and pirB was absent from the 183-kb plasmid in strain VP2HP. A number of protein coding genes from the 183-kb plasmid were also detected in other AHPNS strains. In summary, this study identified a novel 183-kb plasmid that is related to AHPNS causing strains. Homologous recombination of the 69-kb AHPNS plasmid and other naturally occurring plasmids together with loss and gain of AHPNS virulence genes in V. parahaemolyticus were observed. The outcome of this research enables understanding of plasmid dynamics that possibly affect variable degrees of AHPNS pathogenicity. Copyright © 2017 Elsevier B.V. All rights reserved.


July 7, 2019

Targeted disruption of the polyketide synthase gene pks15 affects virulence against insects and phagocytic survival in the fungus Beauveria bassiana.

The reducing clade III polyketide synthase genes, including pks15, are highly conserved among entomopathogenic fungi. To examine the function of pks15, we used targeted disruption to investigate the impact of Beauveria bassiana pks15 on insect pathogenesis. Southern analysis verified that the ?pks15 mutant was disrupted by a single integration of the transformation cassette at the pks15 locus. The ?pks15 mutant had a slight reduction in radial growth, and it produced fewer spores. Our insect bioassays indicated the ?pks15 mutant to be significantly reduced in virulence against beet armyworms compared to wild type (WT), which could be partially accounted for by its markedly decreased ability to survive phagocytosis. Total haemocyte count decreased sharply by 50-fold from days 1-3 post-inoculation in insects infected with WT, compared to a 5-fold decrease in the ?pks15 mutant. The mutant also produced fewer hemolymph hyphal bodies than WT by 3-fold. In co-culture studies with amoebae that have phagocytic ability similar to that of insect haemocytes, at 48 h the mortality rate of amoebae engulfing ?pks15 decreased by 72 %, and ?pks15 CFU decreased by 83 % compared to co-culture with WT. Thus, the ?pks15 mutant had a reduced ability to cope with phagocytosis and highly reduced virulence in an insect host. These data elucidate a mechanism of insect pathogenesis associated with polyketide biosynthesis. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.


July 7, 2019

Comparison of pseudorabies virus China reference strain with emerging variants reveals independent virus evolution within specific geographic regions.

Pseudorabies virus (PRV) China reference strain Ea is genetically closely related to newly emerged variants; however, there is limited information about PRV Ea. Here, we compared PRV Ea with new variant strains by growth kinetics, genome sequencing, and protein expression analysis. Growth analysis showed that strain Ea forms smaller plaques than strain HNX. The full-length genome sequence of Ea revealed that it is clustered in the same subgroup as HNX. Ea and HNX strains exhibited similar extracellular virion protein polymorphisms, whereas strain Bartha expressed less VP26 and more GAPDH. In infected cells, strain Ea expressed high levels of IE180 protein, and Ea and HNX produced higher levels of UL21 protein than strain Bartha. These findings provide evidence that PRV China reference strain Ea is genetically closely related to the newly emerged variant strains, indicating that strain PRV China may have evolved independently leading to the emergence of a variant strain. Copyright © 2017 Elsevier Inc. All rights reserved.


July 7, 2019

Genome comparisons of two Taiwanese community-associated methicillin-resistant Staphylococcus aureus ST59 clones support the multi-origin theory of CA-MRSA.

Sequence type (ST) 59 is an epidemic lineage of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Asia. Two ST59 clones are prevalent in Taiwan: the Taiwan clone (TW) causes severe infections, whereas the Asian-Pacific clone (AP) is usually commensal. In this study, we sequenced the genome and transcriptome of the representative strains of these two clones and found their differences to focus on three mobile genetic elements: TW carries SCCmec Type VT, Panton-Valentine leucocidin (PVL)-encoding prophage FSa2, whereas AP carries SCCmec Type IV and staphylokinase (SAK)-encoding prophage FSa3. The anti-virulent role of SAK was confirmed using murine skin and bloodstream infection models. FSa3 usually integrates into the hlb gene, but in AP was found to be integrated at the genomic island ?Saß. The mutation of the attB site “TGTATCCAAACTGG” to “TGTATCCGAATTGG” led to a failure in the integration of FSa3 in hlb, prompting atypical integration at other sites. The sak gene possessed remarkably different patterns of distribution among the different STs of S. aureus. We conclude that the atypical integration of FSa3 may help S. aureus adapt to the human host habitat and that the subsequent loss of FSa3 contributes toward the development of a virulent CA-MRSA lineage for wider horizontal transmission. Copyright © 2017. Published by Elsevier B.V.


July 7, 2019

Complete genome sequence of Bacillus velezensis LM2303, a biocontrol strain isolated from the dung of wild yak inhabited Qinghai-Tibet plateau.

Bacillus velezensis LM2303 is a biocontrol strain with a broad inhibitory spectrum against plant pathogens, isolated from the dung of wild yak inhabited Qinghai-Tibet plateau, China. Here we present its complete genome sequence, which consists of a single, circular chromosome of 3,989,393bp with a 46.68% G+C content. Genome analysis revealed genes encoding specialized functions for the biosynthesis of antifungal metabolites and antibacterial metabolites, the promotion of plant growth, the alleviation of oxidative stress and nutrient utilization. And the biosynthesis of antimicrobial metabolites in strain LM2303 was confirmed by biochemical analysis, while its plant growth promoting traits were confirmed by inoculation tests. Our results will establish a better foundation for further studies and biocontrol application of B. velezensis LM2303. Copyright © 2017 Elsevier B.V. All rights reserved.


July 7, 2019

First complete genome sequence of Bacillus glycinifermentans B-27.

The first complete genome sequence of Bacillus glycinifermentans B-27 was determined by SMRT sequencing generating a genome sequence with a total length of 4,607,442 bases. Based on this sequence 4738 protein-coding sequences were predicted and used to identify gene clusters that are related to the production of secondary metabolites such as Lichenysin, Bacillibactin and Bacitracin. This genomic potential combined with the ability of B. glycinifermentans B-27 to grown in bile containing media might contribute to a future application of this strain as probiotic in productive livestock potentially inhibiting competing and pathogenic organisms. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.


July 7, 2019

Complete genome sequence of the thermophilic bacterium Geobacillus subterraneus KCTC 3922(T) as a potential denitrifier.

Denitrification is a crucial process for the global nitrogen cycle through the reduction of nitrates by heterotrophic bacteria. Denitrifying microorganisms play an important role in eliminating fixed nitrogen pollutants from the ecosystem, concomitant with N2O emission. Although many microbial denitrifiers have been identified, little is known about the denitrifying ability of the genus Geobacillus. Here, we report the first complete genome sequences of Geobacillus subterraneus KCTC 3922(T), isolated from Liaohe oil field in China, and G. thermodenitrificans KCTC 3902(T). The strain KCTC 3922(T) contains a complete set of genes involved in denitrification, cofactor biogenesis, and transport systems, which is consistent with a denitrifying activity. On the other hand, G. thermodenitrificans KCTC 3902(T) exhibited no denitrifying activity probably due to the lack of molybdnumtransferase (moeA) and nitrite transporter (nirC) genes. Therefore, comparative genome analysis of Geobacillus strains highlights the potential impact on treatment of nitrate-contaminated environments. Copyright © 2017 Elsevier B.V. All rights reserved.


July 7, 2019

Complete genome sequence of a denitrifying bacterium, Pseudomonas sp. CC6-YY-74, isolated from Arctic Ocean sediment

Pseudomonas sp. CC6-YY-74, a psychrotrophic, denitrifying bacterium isolated from Arctic Ocean sediment, uses NO3- or NH4+ as the sole nitrogen source to grow at low temperatures. Here we described the complete genome of Pseudomonas sp. CC6-YY-74. The genome has one circular chromosome of 5,040,792 bp (61.73 mol% G + C content), consisting of 4747 coding genes, 68 tRNA genes, as well as six rRNA operons as 16S-23S-5S rRNA. According to the annotation results, strain CC6-YY-74 encodes 52 proteins related to nitrogen metabolism, including a complete denitrifying pathway, and more than 20 kinds of hydrolytic enzymes.


July 7, 2019

Genomesequencing of Ralstonia solanacearum CQPS-1, a phylotype I strain collected from a highland area with continuous cropping of tobacco.

Ralstonia solanacearum, an agent of bacterial wilt, is a highly variable species with a broad host range and wide geographic distribution. As a species complex, it has extensive genetic diversity and its living environment is polymorphic like the lowland and the highland area, so more genomes are needed for studying population evolution and environment adaptation. In this paper, we reported the genome sequencing of R. solanacearum strain CQPS-1 isolated from wilted tobacco in Pengshui, Chongqing, China, a highland area with severely acidified soil and continuous cropping of tobacco more than 20 years. The comparative genomic analysis among different R. solanacearum strains was also performed. The completed genome size of CQPS-1 was 5.89 Mb and contained the chromosome (3.83 Mb) and the megaplasmid (2.06 Mb). A total of 5229 coding sequences were predicted (the chromosome and megaplasmid encoded 3573 and 1656 genes, respectively). A comparative analysis with eight strains from four phylotypes showed that there was some variation among the species, e.g., a large set of specific genes in CQPS-1. Type III secretion system gene cluster (hrp gene cluster) was conserved in CQPS-1 compared with the reference strain GMI1000. In addition, most genes coding core type III effectors were also conserved with GMI1000, but significant gene variation was found in the gene ripAA: the identity compared with strain GMI1000 was 75% and the hrpII box promoter in the upstream had significantly mutated. This study provided a potential resource for further understanding of the relationship between variation of pathogenicity factors and adaptation to the host environment.


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