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July 7, 2019

Complete genome sequence of Mycoplasma bovis strain 08M.

Mycoplasma bovis is a major bacterial pathogen that can cause respiratory disease, mastitis, and arthritis in cattle. We report here the complete and annotated genome sequence of M. bovis strain 08M, isolated from a calf lung with pneumonia in China. Copyright © 2017 Chen et al.


July 7, 2019

Zinc resistance within swine associated methicillin resistant staphylococcus aureus (MRSA) Isolates in the USA is associated with MLST lineage.

Zinc resistance in livestock-associated methicillin resistant Staphylococcus aureus (LA-MRSA) sequence type (ST) 398 is primarily mediated by the czrC gene co-located with the mecA gene, encoding methicillin resistance, within the type V SCCmec element. Because czrC and mecA are located within the same mobile genetic element, it has been suggested that the use of in feed zinc as an antidiarrheal agent has the potential to contribute to the emergence and spread of MRSA in swine through increased selection pressure to maintain the SCCmec element in isolates obtained from pigs. In this study we report the prevalence of the czrC gene and phenotypic zinc resistance in US swine associated LA-MRSA ST5 isolates, MRSA ST5 isolates from humans with no swine contact, and US swine associated LA-MRSA ST398 isolates. We demonstrate that the prevalence of zinc resistance in US swine associated LA-MRSA ST5 isolates was significantly lower than the prevalence of zinc resistance in MRSA ST5 isolates from humans with no swine contact, swine associated LA-MRSA ST398 isolates, and previous reports describing zinc resistance in other LA-MRSA ST398 isolates. Collectively our data suggest that selection pressure associated with zinc supplementation in feed is unlikely to have played a significant role in the emergence of LA-MRSA ST5 in the US swine population. Additionally, our data indicate that zinc resistance is associated with MLST lineage suggesting a potential link between genetic lineage and carriage of resistance determinants.Importance Our data suggest that coselection thought to be associated with the use of zinc in feed as an antimicrobial agent is not playing a role in the emergence of livestock-associated methicillin resistant Staphylococcus aureus (LA-MRSA) ST5 in the US swine population. Additionally, our data indicate that zinc resistance is more associated with multi locus sequence type (MLST) lineage suggesting a potential link between genetic lineage and carriage of resistance markers. This information is important to public health professionals, veterinarians, producers, and consumers. Copyright © 2017 American Society for Microbiology.


July 7, 2019

Genome mining and predictive functional profiling of acidophilic rhizobacterium Pseudomonas fluorescens Pt14.

Pseudomonas fluorescens Pt14 is a non-pathogenic and acidophilic bacterium isolated from acidic soil (pH 4.65). Genome sequencing of strain Pt14 was performed using Single Molecule Real Time (SMRT) sequencing to get insights into unique existence of this strain in acidic environment. Complete genome sequence of this strain revealed a chromosome of 5,841,722 bp having 5354 CDSs and 88 RNAs. Phylogenomic reconstruction based on 16S rRNA gene, Average Nucleotide Identity (ANI) values and marker proteins revealed that strain Pt14 shared a common clade with P. fluorescens strain A506 and strain SS101. ANI value of strain Pt14 in relation to strain A506 was found 99.23% demonstrating a very close sub-species association at genome level. Further, orthology determination among these three phylogenetic neighbors revealed 4726 core proteins. Functional analysis elucidated significantly higher abundance of sulphur metabolism (>1×) which could be one of the reasons for the survival of strain Pt14 under acidic conditions (pH 4.65). Acidophilic bacteria have capability to oxidize sulphur into sulphuric acid which in turn can make the soil acidic and genome-wide analysis of P. fluorescens Pt14 demonstrated that this strain contributes towards making the soil acidic.


July 7, 2019

Genome-wide analysis of gene expression and protein secretion of Babesia canis during virulent infection identifies potential pathogenicity factors.

Infections of dogs with virulent strains of Babesia canis are characterized by rapid onset and high mortality, comparable to complicated human malaria. As in other apicomplexan parasites, most Babesia virulence factors responsible for survival and pathogenicity are secreted to the host cell surface and beyond where they remodel and biochemically modify the infected cell interacting with host proteins in a very specific manner. Here, we investigated factors secreted by B. canis during acute infections in dogs and report on in silico predictions and experimental analysis of the parasite’s exportome. As a backdrop, we generated a fully annotated B. canis genome sequence of a virulent Hungarian field isolate (strain BcH-CHIPZ) underpinned by extensive genome-wide RNA-seq analysis. We find evidence for conserved factors in apicomplexan hemoparasites involved in immune-evasion (e.g. VESA-protein family), proteins secreted across the iRBC membrane into the host bloodstream (e.g. SA- and Bc28 protein families), potential moonlighting proteins (e.g. profilin and histones), and uncharacterized antigens present during acute crisis in dogs. The combined data provides a first predicted and partially validated set of potential virulence factors exported during fatal infections, which can be exploited for urgently needed innovative intervention strategies aimed at facilitating diagnosis and management of canine babesiosis.


July 7, 2019

Evidence for the evolutionary steps leading to mecA-mediated ß-lactam resistance in staphylococci.

The epidemiologically most important mechanism of antibiotic resistance in Staphylococcus aureus is associated with mecA-an acquired gene encoding an extra penicillin-binding protein (PBP2a) with low affinity to virtually all ß-lactams. The introduction of mecA into the S. aureus chromosome has led to the emergence of methicillin-resistant S. aureus (MRSA) pandemics, responsible for high rates of mortality worldwide. Nonetheless, little is known regarding the origin and evolution of mecA. Different mecA homologues have been identified in species belonging to the Staphylococcus sciuri group representing the most primitive staphylococci. In this study we aimed to identify evolutionary steps linking these mecA precursors to the ß-lactam resistance gene mecA and the resistance phenotype. We sequenced genomes of 106 S. sciuri, S. vitulinus and S. fleurettii strains and determined their oxacillin susceptibility profiles. Single-nucleotide polymorphism (SNP) analysis of the core genome was performed to assess the genetic relatedness of the isolates. Phylogenetic analysis of the mecA gene homologues and promoters was achieved through nucleotide/amino acid sequence alignments and mutation rates were estimated using a Bayesian analysis. Furthermore, the predicted structure of mecA homologue-encoded PBPs of oxacillin-susceptible and -resistant strains were compared. We showed for the first time that oxacillin resistance in the S. sciuri group has emerged multiple times and by a variety of different mechanisms. Development of resistance occurred through several steps including structural diversification of the non-binding domain of native PBPs; changes in the promoters of mecA homologues; acquisition of SCCmec and adaptation of the bacterial genetic background. Moreover, our results suggest that it was exposure to ß-lactams in human-created environments that has driven evolution of native PBPs towards a resistance determinant. The evolution of ß-lactam resistance in staphylococci highlights the numerous resources available to bacteria to adapt to the selective pressure of antibiotics.


July 7, 2019

Updated reference genome sequence and annotation of Mycobacterium bovis AF2122/97.

We report here an update to the reference genome sequence of the bovine tuberculosis bacillus Mycobacterium bovis AF2122/97, generated using an integrative multiomics approach. The update includes 42 new coding sequences (CDSs), 14 modified annotations, 26 single-nucleotide polymorphism (SNP) corrections, and disclosure that the RD900 locus, previously described as absent from the genome, is in fact present. Copyright © 2017 Malone et al.


July 7, 2019

Comparative genomics of all three Campylobacter sputorum biovars and a novel cattle-associated C. sputorum clade.

Campylobacter sputorum is a non-thermotolerant campylobacter that is primarily isolated from food animals such as cattle and sheep. C. sputorum is also infrequently associated with human illness. Based on catalase and urease activity, three biovars are currently recognized within C. sputorum: bv. sputorum (catalase negative, urease negative), bv. fecalis (catalase positive, urease negative), and bv. paraureolyticus (catalase negative, urease positive). A multi-locus sequence typing (MLST) method was recently constructed for C. sputorum. MLST typing of several cattle-associated C. sputorum isolates suggested that they are members of a divergent C. sputorum clade. Although catalase positive, and thus technically bv. fecalis, the taxonomic position of these strains could not be determined solely by MLST. To further characterize C. sputorum, the genomes of four strains, representing all three biovars and the divergent clade, were sequenced to completion. Here we present a comparative genomic analysis of the four C. sputorum genomes. This analysis indicates that the three biovars and the cattle-associated strains are highly-related at the genome level with similarities in gene content. Furthermore, the four genomes are strongly syntenic with one or two minor inversions. However, substantial differences in gene content were observed among the three biovars. Finally, although the strain representing the cattle-associated isolates was shown to be C. sputorum, it is possible that this strain is a member of a novel C. sputorum subspecies; thus, these cattle-associated strains may form a second taxon within C. sputorum. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution 2017. This work is written by US Government employees and is in the public domain in the US.


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

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

Characterization of NDM-5-positive extensively resistant Escherichia coli isolates from dairy cows.

The aim of this study was to investigate the prevalence of blaNDM-5 gene in Escherichia coli isolates from dairy cows and to characterize the molecular traits of the blaNDM-5-positive isolates. A total of 169 cows were sampled (169 feces and 169 raw milk samples) in three dairy farms in Jiangsu Province and 203 E. coli isolates were recovered. Among these strains, three isolates carried blaNDM-5 gene, including one co-harboring mcr-1, which belonged to sequence type 446 and the other two belonged to ST2. Susceptibility testing revealed that the three blaNDM-5-positive isolates showed extensive resistance to antimicrobials. The blaNDM-5 gene was located on a ~46-kb IncX3 transferrable pNDM-MGR194-like plasmid in all three isolates, while mcr-1 was located on a ~260-kb IncHI2 plasmid pXGE1mcr. Competition experiments revealed that acquisition of blaNDM-5 or mcr-1-bearing plasmid can incur fitness cost of bacterial host, however, plasmid stability testing showed that both blaNDM-5 and mcr-1-carrying plasmid maintained stable in the hosts after ten passages without antimicrobial selection. Whole genome sequencing revealed that the mcr-1 gene coexisted with multiple resistance genes in pXGE1mcr and the backbone of this plasmid was similar to that of previously reported mcr-1-positive plasmid pHNSHP45-2. Moreover, pXGE1mcr could be conjugated into clinical NDM-5-positive E. coli isolates in vitro, thereby generating strains that approached pan-resistance. Active surveillance efforts are imperative to monitor the prevalence of blaNDM-5 and mcr-1 in carbapenem-resistant Enterobacteriaceae from dairy farms throughout China. Copyright © 2017 Elsevier B.V. All rights reserved.


July 7, 2019

Clostridium chauvoei, an evolutionary dead-end pathogen.

Full genome sequences of 20 strains of Clostridium chauvoei, the etiological agent of blackleg of cattle and sheep, isolated from four different continents over a period of 64 years (1951-2015) were determined and analyzed. The study reveals that the genome of the species C. chauvoei is highly homogeneous compared to the closely related species C. perfringens, a widespread pathogen that affects human and many animal species. Analysis of the CRISPR locus is sufficient to differentiate most C. chauvoei strains and is the most heterogenous region in the genome, containing in total 187 different spacer elements that are distributed as 30 – 77 copies in the various strains. Some genetic differences are found in the 3 allelic variants of fliC1, fliC2 and fliC3 genes that encode structural flagellin proteins, and certain strains do only contain one or two alleles. However, the major virulence genes including the highly toxic C.chauvoei toxin A, the sialidase and the two hyaluronidases are fully conserved as are the metabolic and structural genes of C. chauvoei. These data indicate that C. chauvoei is a strict ruminant-associated pathogen that has reached a dead end in its evolution.


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