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April 21, 2020  |  

Complete genome sequence provides insights into the quorum sensing-related spoilage potential of Shewanella baltica 128 isolated from spoiled shrimp.

Shewanella baltica 128 is a specific spoilage organism (SSO) isolated from the refrigerated shrimp that results in shrimp spoilage. This study reported the complete genome sequencing of this strain, with the primary annotations associated with amino acid transport and metabolism (8.66%), indicating that S. baltica 128 has good potential for degrading proteins. In vitro experiments revealed Shewanella baltica 128 could adapt to the stress conditions by regulating its growth and biofilm formation. Genes that related to the spoilage-related metabolic pathways, including trimethylamine metabolism (torT), sulfur metabolism (cysM), putrescine metabolism (speC), biofilm formation (rpoS) and serine protease production (degS), were identified. Genes (LuxS, pfs, LuxR and qseC) that related to the specific QS system were also identified. Complete genome sequence of S. baltica 128 provide insights into the QS-related spoilage potential, which might provide novel information for the development of new approaches for spoilage detection and prevention based on QS target.Copyright © 2019. Published by Elsevier Inc.

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April 21, 2020  |  

Increased prevalence of Escherichia coli strains from food carrying blaNDM and mcr-1-bearing plasmids that structurally resemble those of clinical strains, China, 2015 to 2017.

Introduction: Emergence of resistance determinants of blaNDM and mcr-1 has undermined the antimicrobial effectiveness of the last line drugs carbapenems and colistin. Aim: This work aimed to assess the prevalence of blaNDM and mcr-1 in E. coli strains collected from food in Shenzhen, China, during the period 2015 to 2017. Methods: Multidrug-resistant E. coli strains were isolated from food samples. Plasmids encoding mcr-1 or blaNDM genes were characterised and compared with plasmids found in clinical isolates.ResultsAmong 1,166 non-repeated cephalosporin-resistant E. coli strains isolated from 2,147 food samples, 390 and 42, respectively, were resistant to colistin and meropenem, with five strains being resistant to both agents. The rate of resistance to colistin increased significantly (p?

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April 21, 2020  |  

Complete Sequence of a Novel Multidrug-Resistant Pseudomonas putida Strain Carrying Two Copies of qnrVC6.

This study aimed at identification and characterization of a novel multidrug-resistant Pseudomonas putida strain Guangzhou-Ppu420 carrying two copies of qnrVC6 isolated from a hospital in Guangzhou, China, in 2012. Antimicrobial susceptibility was tested by Vitek2™ Automated Susceptibility System and Etest™ strips, and whole-genome sequencing facilitated analysis of its multidrug resistance. The genome has a length of 6,031,212?bp and an average G?+?C content of 62.01%. A total of 5,421 open reading frames were identified, including eight 5S rRNA, seven 16S rRNA, and seven 23S rRNA, and 76 tRNA genes. Importantly, two copies of qnrVC6 gene with three ISCR1 around, a blaVIM-2 carrying integron In528, a novel gcu173 carrying integron In1348, and six antibiotic resistance genes were identified. This is the first identification of two copies of the qnrVC6 gene in a single P. putida isolate and a class 1 integron In1348.

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April 21, 2020  |  

Sensitivity to the two peptide bacteriocin plantaricin EF is dependent on CorC, a membrane-bound, magnesium/cobalt efflux protein.

Lactic acid bacteria produce a variety of antimicrobial peptides known as bacteriocins. Most bacteriocins are understood to kill sensitive bacteria through receptor-mediated disruptions. Here, we report on the identification of the Lactobacillus plantarum plantaricin EF (PlnEF) receptor. Spontaneous PlnEF-resistant mutants of the PlnEF-indicator strain L. plantarum NCIMB 700965 (LP965) were isolated and confirmed to maintain cellular ATP levels in the presence of PlnEF. Genome comparisons resulted in the identification of a single mutated gene annotated as the membrane-bound, magnesium/cobalt efflux protein CorC. All isolates contained a valine (V) at position 334 instead of a glycine (G) in a cysteine-ß-synthase domain at the C-terminal region of CorC. In silico template-based modeling of this domain indicated that the mutation resides in a loop between two ß-strands. The relationship between PlnEF, CorC, and metal homeostasis was supported by the finding that PlnEF-resistance was lost when PlnEF was applied together with high concentrations of Mg2+ , Co2+ , Zn2+ , or Cu2+ . Lastly, PlnEF sensitivity was increased upon heterologous expression of LP965 corC but not the G334V CorC mutant in the PlnEF-resistant strain Lactobacillus casei BL23. These results show that PlnEF kills sensitive bacteria by targeting CorC. © 2019 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

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April 21, 2020  |  

In-depth analysis of the genome of Trypanosoma evansi, an etiologic agent of surra.

Trypanosoma evansi is the causative agent of the animal trypanosomiasis surra, a disease with serious economic burden worldwide. The availability of the genome of its closely related parasite Trypanosoma brucei allows us to compare their genetic and evolutionarily shared and distinct biological features. The complete genomic sequence of the T. evansi YNB strain was obtained using a combination of genomic and transcriptomic sequencing, de novo assembly, and bioinformatic analysis. The genome size of the T. evansi YNB strain was 35.2 Mb, showing 96.59% similarity in sequence and 88.97% in scaffold alignment with T. brucei. A total of 8,617 protein-coding genes, accounting for 31% of the genome, were predicted. Approximately 1,641 alternative splicing events of 820 genes were identified, with a majority mediated by intron retention, which represented a major difference in post-transcriptional regulation between T. evansi and T. brucei. Disparities in gene copy number of the variant surface glycoprotein, expression site-associated genes, microRNAs, and RNA-binding protein were clearly observed between the two parasites. The results revealed the genomic determinants of T. evansi, which encoded specific biological characteristics that distinguished them from other related trypanosome species.

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April 21, 2020  |  

Retrospective whole-genome sequencing analysis distinguished PFGE and drug-resistance-matched retail meat and clinical Salmonella isolates.

Non-typhoidal Salmonella is a leading cause of outbreak and sporadic-associated foodborne illnesses in the United States. These infections have been associated with a range of foods, including retail meats. Traditionally, pulsed-field gel electrophoresis (PFGE) and antibiotic susceptibility testing (AST) have been used to facilitate public health investigations of Salmonella infections. However, whole-genome sequencing (WGS) has emerged as an alternative tool that can be routinely implemented. To assess its potential in enhancing integrated surveillance in Pennsylvania, USA, WGS was used to directly compare the genetic characteristics of 7 retail meat and 43 clinical historic Salmonella isolates, subdivided into 3 subsets based on PFGE and AST results, to retrospectively resolve their genetic relatedness and identify antimicrobial resistance (AMR) determinants. Single nucleotide polymorphism (SNP) analyses revealed that the retail meat isolates within S. Heidelberg, S. Typhimurium var. O5- subset 1 and S. Typhimurium var. O5- subset 2 were separated from each primary PFGE pattern-matched clinical isolate by 6-12, 41-96 and 21-81 SNPs, respectively. Fifteen resistance genes were identified across all isolates, including fosA7, a gene only recently found in a limited number of Salmonella and a =95?%?phenotype to genotype correlation was observed for all tested antimicrobials. Moreover, AMR was primarily plasmid-mediated in S. Heidelberg and S. Typhimurium var. O5- subset 2, whereas AMR was chromosomally carried in S. Typhimurium var. O5- subset 1. Similar plasmids were identified in both the retail meat and clinical isolates. Collectively, these data highlight the utility of WGS in retrospective analyses and enhancing integrated surveillance for Salmonella from multiple sources.

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April 21, 2020  |  

Complete genome sequence unveiled cellulose degradation enzymes and secondary metabolic potentials in Streptomyces sp. CC0208.

Marine Streptomyces sp. CC0208 isolated from the Bohai Bay showed high efficiency of cellulose degradation under optimized fermentation parameters. Also, as one of the bioinformatics-based approaches for the discovery of novel natural product and enzyme effectively, genome mining has been developed and applied widely. Herein, we reported the complete genome sequence of Streptomyces sp. CC0208.Whole-genome sequencing analysis revealed a genome size of 9,325,981?bp with a linear chromosome, GC content of 70.59% and 8487 protein-coding genes. Abundant genes have predicted functions in antibiotic metabolism and enzymes. A 20 enzymes closely associated with cellulose degradation were discovered. A total of 25 biosynthetic gene clusters (BGCs) of secondary metabolites were identified, including diverse classes of natural products. The availability of genome sequence of Streptomyces sp. CC0208 not only will assist in cracking the mechanism of cellulose degradation but also will provide the insights into the significant secondary metabolic potentials for the production of diverse compound classes based on rational strategies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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April 21, 2020  |  

The complete mitochondrial genome of the tartar Sand Boa Eryx tataricus

Eryx is a genus of snakes belonging to the family Boidae. In this study, the mitochondrial genome sequence of Eryx tataricus was generated using a PacBio RSII DNA sequencer employing the single mol- ecule, real-time sequencing technology. A maximum-likelihood (ML) phylogenetic tree of 26 snakes was re-constructed based on the 13 protein-coding genes for convincing the mitochondrial DNA sequences.

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April 21, 2020  |  

Assessment of the microbial diversity of Chinese Tianshan tibicos by single molecule, real-time sequencing technology.

Chinese Tianshan tibico grains were collected from the rural area of Tianshan in Xinjiang province, China. Typical tibico grains are known to consist of polysaccharide matrix that embeds a variety of bacteria and yeasts. These grains are widely used in some rural regions to produce a beneficial sugary beverage that is slightly acidic and contains low level of alcohol. This work aimed to characterize the microbiota composition of Chinese Tianshan tibicos using the single molecule, real-time sequencing technology, which is advantageous in generating long reads. Our results revealed that the microbiota mainly comprised of the bacterial species of Lactobacillus hilgardii, Lactococcus raffinolactis, Leuconostoc mesenteroides, Zymomonas mobilis, together with a Guehomyces pullulans-dominating fungal community. The data generated in this work helps identify beneficial microbes in Chinese Tianshan tibico grains.

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April 21, 2020  |  

Genome of the Komodo dragon reveals adaptations in the cardiovascular and chemosensory systems of monitor lizards.

Monitor lizards are unique among ectothermic reptiles in that they have high aerobic capacity and distinctive cardiovascular physiology resembling that of endothermic mammals. Here, we sequence the genome of the Komodo dragon Varanus komodoensis, the largest extant monitor lizard, and generate a high-resolution de novo chromosome-assigned genome assembly for V. komodoensis using a hybrid approach of long-range sequencing and single-molecule optical mapping. Comparing the genome of V. komodoensis with those of related species, we find evidence of positive selection in pathways related to energy metabolism, cardiovascular homoeostasis, and haemostasis. We also show species-specific expansions of a chemoreceptor gene family related to pheromone and kairomone sensing in V. komodoensis and other lizard lineages. Together, these evolutionary signatures of adaptation reveal the genetic underpinnings of the unique Komodo dragon sensory and cardiovascular systems, and suggest that selective pressure altered haemostasis genes to help Komodo dragons evade the anticoagulant effects of their own saliva. The Komodo dragon genome is an important resource for understanding the biology of monitor lizards and reptiles worldwide.

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April 21, 2020  |  

PacBio sequencing reveals bacterial community diversity in cheeses collected from different regions.

Cheese is a fermented dairy product that is popular for its unique flavor and nutritional value. Recent studies have shown that microorganisms in cheese play an important role in the fermentation process and determine the quality of the cheese. We collected 12 cheese samples from different regions and studied the composition of their bacterial communities using PacBio small-molecule real-time sequencing (Pacific Biosciences, Menlo Park, CA). Our data revealed 144 bacterial genera (including Lactobacillus, Streptococcus, Lactococcus, and Staphylococcus) and 217 bacterial species (including Lactococcus lactis, Streptococcus thermophilus, Staphylococcus equorum, and Streptococcus uberis). We investigated the flavor quality of the cheese samples using an electronic nose system and we found differences in flavor-quality indices among samples from different regions. We found a clustering tendency based on flavor quality using principal component analysis. We found correlations between lactic acid bacteria and the flavor quality of the cheese samples. Biodegradation and metabolism of xenobiotics, and lipid-metabolism-related pathways, were predicted to contribute to differences in cheese flavor using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). This preliminary study explored the bacterial communities in cheeses collected from different regions and their potential genome functions from the perspective of flavor quality.Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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April 21, 2020  |  

Mutation of a bHLH transcription factor allowed almond domestication.

Wild almond species accumulate the bitter and toxic cyanogenic diglucoside amygdalin. Almond domestication was enabled by the selection of genotypes harboring sweet kernels. We report the completion of the almond reference genome. Map-based cloning using an F1 population segregating for kernel taste led to the identification of a 46-kilobase gene cluster encoding five basic helix-loop-helix transcription factors, bHLH1 to bHLH5. Functional characterization demonstrated that bHLH2 controls transcription of the P450 monooxygenase-encoding genes PdCYP79D16 and PdCYP71AN24, which are involved in the amygdalin biosynthetic pathway. A nonsynonymous point mutation (Leu to Phe) in the dimerization domain of bHLH2 prevents transcription of the two cytochrome P450 genes, resulting in the sweet kernel trait. Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

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April 21, 2020  |  

Comprehensive identification of the full-length transcripts and alternative splicing related to the secondary metabolism pathways in the tea plant (Camellia sinensis).

Flavonoids, theanine and caffeine are the main secondary metabolites of the tea plant (Camellia sinensis), which account for the tea’s unique flavor quality and health benefits. The biosynthesis pathways of these metabolites have been extensively studied at the transcriptional level, but the regulatory mechanisms are still unclear. In this study, to explore the transcriptome diversity and complexity of tea plant, PacBio Iso-Seq and RNA-seq analysis were combined to obtain full-length transcripts and to profile the changes in gene expression during the leaf development. A total of 1,388,066 reads of insert (ROI) were generated with an average length of 1,762?bp, and more than 54% (755,716) of the ROIs were full-length non-chimeric (FLNC) reads. The Benchmarking Universal Single-Copy Orthologue (BUSCO) completeness was 92.7%. A total of 93,883 non-redundant transcripts were obtained, and 87,395 (93.1%) were new alternatively spliced isoforms. Meanwhile, 7,650 differential expression transcripts (DETs) were identified. A total of 28,980 alternative splicing (AS) events were predicted, including 1,297 differential AS (DAS) events. The transcript isoforms of the key genes involved in the flavonoid, theanine and caffeine biosynthesis pathways were characterized. Additionally, 5,777 fusion transcripts and 9,052 long non-coding RNAs (lncRNAs) were also predicted. Our results revealed that AS potentially plays a crucial role in the regulation of the secondary metabolism of the tea plant. These findings enhanced our understanding of the complexity of the secondary metabolic regulation of tea plants and provided a basis for the subsequent exploration of the regulatory mechanisms of flavonoid, theanine and caffeine biosynthesis in tea plants.

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April 21, 2020  |  

Characterization of an NDM-5 carbapenemase-producing Escherichia coli ST156 isolate from a poultry farm in Zhejiang, China.

The emergence of carbapenem-resistant Enterobacteriaceae strains has posed a severe threat to public health in recent years. The mobile elements carrying the New Delhi metallo-ß-lactqtamase (NDM) gene have been regarded as the major mechanism leading to the rapid increase of carbapenem-resistant Enterobacteriaceae strains isolated from clinics and animals.We describe an NDM-5-producing Escherichia coli strain, ECCRA-119 (sequence type 156 [ST156]), isolated from a poultry farm in Zhejiang, China. ECCRA-119 is a multidrug-resistant (MDR) isolate that exhibited resistance to 27 antimicrobial compounds, including imipenem and meropenem, as detected by antimicrobial susceptibility testing (AST). The complete genome sequence of the ECCRA-119 isolate was also obtained using the PacBio RS II platform. Eleven acquired resistance genes were identified in the chromosome; four were detected in plasmid pTB201, while six were detected in plasmid pTB202. Importantly, the carbapenem-resistant gene blaNDM-5 was detected in the IncX3 plasmid pTB203. In addition, seven virulence genes and one metal-resistance gene were also detected. The results of conjugation experiments and the transfer regions identification indicated that the blaNDM-5-harboring plasmid pTB203 could be transferred between E. coli strains.The results reflected the severe bacterial resistance in a poultry farm in Zhejiang province and increased our understanding of the presence and transmission of the blaNDM-5 gene.

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