April 21, 2020  |  

Chryseobacterium mulctrae sp. nov., isolated from raw cow’s milk.

A Gram-stain-negative bacterial strain, designated CA10T, was isolated from bovine raw milk sampled in Anseong, Republic of Korea. Cells were yellow-pigmented, aerobic, non-motile bacilli and grew optimally at 30?°C and pH 7.0 on tryptic soy agar without supplementation of NaCl. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain CA10T belonged to the genus Chryseobacterium, family Flavobacteriaceae, and was most closely related to Chryseobacterium indoltheticum ATCC 27950T (98.75?% similarity). The average nucleotide identity and digital DNA-DNA hybridization values of strain CA10T were 94.4 and 56.9?%, respectively, relative to Chryseobacterium scophthalmum DSM 16779T, being lower than the cut-off values of 95-96?and 70?%, respectively. The predominant respiratory quinone was menaquinone-6; major polar lipid, phosphatidylethanolamine; major fatty acids, iso-C15?:?0, summed feature 9 (iso-C17?:?1?9c and/or C16?:?0 10-methyl), summed feature 3 (iso-C15?:?0 2-OH and/or C16?:?1?7c) and iso-C17?:?0 3-OH. The results of physiological, chemotaxonomic and biochemical analyses suggested that strain CA10T is a novel species of genus Chryseobacterium, for which the name Chryseobacterium mulctrae sp. nov. is proposed. The type strain is CA10T (=KACC 21234T=JCM 33443T).


April 21, 2020  |  

Allopseudarcicella aquatilis gen. nov., sp. nov., isolated from freshwater.

A Gram-stain-negative, rod-shaped and red-pigmented strain, HME7025T, was isolated from freshwater sampled in the Republic of Korea. Phylogenetic analysis based on its 16S rRNA gene sequence revealed that strain HME7025T formed a lineage within the family Cytophagaceae of the phylum Bacteroidetes. Strain HME7025T was closely related to the genera Pseudarcicella, Arcicella and Flectobacillus. The 16S rRNA gene sequence similarity values of strain HME7025T were under 94.5?% to its closest phylogenetic neighbours. The major fatty acids of strain HME7025T were iso-C15?:?0 (41.9?%), summed feature 3 (comprising C16?:?1?7c and/or C16?:?1?6c; 12.2?%) and anteiso-C15?:?0 (10.8?%). The major respiratory quinone was menaquinone-7. The major polar lipids were phosphatidylethanolamine, two unidentified aminophospholipids and one unidentified polar lipid. The DNA G+C content of strain HME7025T was 37.9?mol%. On the basis of the evidence presented in this study, strain HME7025T represents a novel species of a novel genus within the family Cytophagaceae, for which the name Allopseudarcicella aquatilis gen. nov., sp. nov. is proposed. The type strain is HME7025T (=KCTC 23617T=CECT 7957T).


April 21, 2020  |  

Complete genome sequence of Antarcticibacterium flavum JB01H24T from an Antarctic marine sediment

Antarcticibacterium flavum JB01H24T was isolated from a marine sediment of the Ross Sea, Antarctica. Whole-genome sequencing of the strain Antarcticibacterium flavum JB01H24T was achieved using PacBio RS II platform. The resulting complete genome comprised of one closed, complete chromosome of 4,319,074 base pairs with a 40.87% G?+?C content, where genomic analyses demonstrated that it is constituted mostly by putative ORFs with unknown functions, representing a novel genetic feature. It is the first complete genome sequence of the Antarcticibacterium strain.


April 21, 2020  |  

The complete genome sequence and comparative genome analysis of the multi-drug resistant food-borne pathogen Bacillus cereus.

Bacillus cereus is an opportunistic human pathogen causing food-borne gastrointestinal infections and non-gastrointestinal infections worldwide. The strain B. cereus FORC_013 was isolated from fried eel. Its genome was completely sequenced by PacBio technology, analyzed and compared with other complete genome sequences of Bacillus to elucidate the distinct pathogenic features of the strain isolated in South Korea. Genomic analysis revealed pathogenesis and host immune evasion-associated genes encoding tissue-destructive exoenzymes, and pore-forming toxins. In particular, tissue-destructive (hemolysin BL, nonhaemolytic enterotoxins) and cytolytic proteins (cytolysin) were observed in the genome, which damage the plasma membrane of the epithelial cells of the small intestine causing diarrhea in humans. Capsule biosynthesis gene found in both chromosome and plasmid, which might be responsible for protecting the pathogen from the host cell immune defense system after host cell invasion. Additionally, multidrug resistance operon and efflux pumps were identified in the genome, which play a prominent role in multi-antibiotic resistance. Comparative phylogenetic tree analysis of the strain FORC_013 and other B. cereus strains revealed that the closest strains are ATCC 14579 and B4264. This genome data can be used to identify virulence factors that can be applied for the development of novel biomarkers for the rapid detection of this pathogen in foods.Copyright © 2018. Published by Elsevier Inc.


April 21, 2020  |  

Tracking short-term changes in the genetic diversity and antimicrobial resistance of OXA-232-producing Klebsiella pneumoniae ST14 in clinical settings.

To track stepwise changes in genetic diversity and antimicrobial resistance in rapidly evolving OXA-232-producing Klebsiella pneumoniae ST14, an emerging carbapenem-resistant high-risk clone, in clinical settings.Twenty-six K. pneumoniae ST14 isolates were collected by the Korean Nationwide Surveillance of Antimicrobial Resistance system over the course of 1 year. Isolates were subjected to whole-genome sequencing and MIC determinations using 33 antibiotics from 14 classes.Single-nucleotide polymorphism (SNP) typing identified 72 unique SNP sites spanning the chromosomes of the isolates, dividing them into three clusters (I, II and III). The initial isolate possessed two plasmids with 18 antibiotic-resistance genes, including blaOXA-232, and exhibited resistance to 11 antibiotic classes. Four other plasmids containing 12 different resistance genes, including blaCTX-M-15 and strA/B, were introduced over time, providing additional resistance to aztreonam and streptomycin. Moreover, chromosomal integration of insertion sequence Ecp1-blaCTX-M-15 mediated the inactivation of mgrB responsible for colistin resistance in four isolates from cluster III. To the best of our knowledge, this is the first description of K. pneumoniae ST14 resistant to both carbapenem and colistin in South Korea. Furthermore, although some acquired genes were lost over time, the retention of 12 resistance genes and inactivation of mgrB provided resistance to 13 classes of antibiotics.We describe stepwise changes in OXA-232-producing K. pneumoniae ST14 in vivo over time in terms of antimicrobial resistance. Our findings contribute to our understanding of the evolution of emerging high-risk K. pneumoniae clones and provide reference data for future outbreaks.Copyright © 2019 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.


April 21, 2020  |  

Analyses of the Complete Genome Sequence of the Strain Bacillus pumilus ZB201701 Isolated from Rhizosphere Soil of Maize under Drought and Salt Stress.

Bacillus pumilus ZB201701 is a rhizobacterium with the potential to promote plant growth and tolerance to drought and salinity stress. We herein present the complete genome sequence of the Gram-positive bacterium B. pumilus ZB201701, which consists of a linear chromosome with 3,640,542 base pairs, 3,608 protein-coding sequences, 24 ribosomal RNAs, and 80 transfer RNAs. Genome analyses using bioinformatics revealed some of the putative gene clusters involved in defense mechanisms. In addition, activity analyses of the strain under salt and simulated drought stress suggested its potential tolerance to abiotic stress. Plant growth-promoting bacteria-based experiments indicated that the strain promotes the salt tolerance of maize. The complete genome of B. pumilus ZB201701 provides valuable insights into rhizobacteria-mediated salt and drought tolerance and rhizobacteria-based solutions for abiotic stress in agriculture.


April 21, 2020  |  

Characterization of Extracellular Biosurfactants Expressed by a Pseudomonas putida Strain Isolated from the Interior of Healthy Roots from Sida hermaphrodita Grown in a Heavy Metal Contaminated Soil.

Pseudomonas putida E41 isolated from root interior of Sida hermaphrodita (grown on a field contaminated with heavy metals) showed high biosurfactant activity. In this paper, we describe data from mass spectrometry and genome analysis, to improve our understanding on the phenotypic properties of the strain. Supernatant derived from P. putida E41 liquid culture exhibited a strong decrease in the surface tension accompanied by the ability for emulsion stabilization. We identified extracellular lipopeptides, putisolvin I and II expression but did not detect rhamnolipids. Their presence was confirmed by matrix-assisted laser desorption and ionization (MALDI) TOF/TOF technique. Moreover, ten phospholipids (mainly phosphatidylethanolamines PE 33:1 and PE 32:1) which were excreted by vesicles were also detected. In contrast the bacterial cell pellet was dominated by phosphatidylglycerols (PGs), which were almost absent in the supernatant. It seems that the composition of extracellular (secreted to the environment) and cellular lipids in this strain differs. Long-read sequencing and complete genome reconstruction allowed the identification of a complete putisolvin biosynthesis pathway. In the genome of P. putida E41 were also found all genes involved in glycerophospholipid biosynthesis, and they are likely responsible for the production of detected phospholipids. Overall this is the first report describing the expression of extracellular lipopeptides (identified as putisolvins) and phospholipids by a P. putida strain, which might be explained by the need to adapt to the highly contaminated environment.


April 21, 2020  |  

Complete Genome Sequence of strain WHRI 3811, race 1 of Xanthomonas campestris pv. campestris, the Causal Agent of Black Rot of Cruciferous Vegetables.

Xanthomonas campestris pv. campestris (Xcc) is an important bacterial pathogen that causes black rot and brings about enormous production loss for cruciferous vegetables worldwide. Currently, genome sequences for only a few Xcc isolates are available, most of which are draft ones. Based on the next-generation sequencing (NGS) and single-molecule sequencing in real time (SMRT) technologies, we present here the complete genome sequence of strain WHRI 3811, race 1 of Xcc, which is a type strain that has been extensively used. The genome data will contribute to our understanding of Xcc genomic features, and pave the way for research on Xcc-host interactions.


April 21, 2020  |  

Complete Genome Sequence of a Chlorobenzene Degrader, Pandoraea pnomenusa MCB032.

Chlorobenzenes are ubiquitously distributed, highly persistent, and toxic environmental contaminants. Pandoraea pnomenusa MCB032 was isolated as a new dominant chlorobenzene-utilizing strain from a functionally stable bioreactor during the treatment of chlorobenzenes when strain Burkholderia sp. JS150 disappeared. In study, we report the complete genome sequence of strain MCB032 which consists of a circular chromosome and three plasmids, which are?~?6 Mb in length with 5450 open reading frames-12 encoding rRNAs and 77 encoding tRNAs. We further identified 17 putative genes encoding the enzymes involved in the methyl-accepting chemotaxis proteins in sensing chemical gradients during chemotaxis. The annotated complete genome sequence of this strain will provide genetic insights into the degradation of chlorinated aromatic compounds. The information will empower the elucidation of chlorobenzene affinity hierarchy and species succession in the bioreactor.


April 21, 2020  |  

Biochemical characterization of a novel cold-adapted agarotetraose-producing a-agarase, AgaWS5, from Catenovulum sediminis WS1-A.

Although many ß-agarases that hydrolyze the ß-1,4 linkages of agarose have been biochemically characterized, only three a-agarases that hydrolyze the a-1,3 linkages are reported to date. In this study, a new a-agarase, AgaWS5, from Catenovulum sediminis WS1-A, a new agar-degrading marine bacterium, was biochemically characterized. AgaWS5 belongs to the glycoside hydrolase (GH) 96 family. AgaWS5 consists of 1295 amino acids (140 kDa) and has the 65% identity to an a-agarase, AgaA33, obtained from an agar-degrading bacterium Thalassomonas agarivorans JAMB-A33. AgaWS5 showed the maximum activity at a pH and temperature of 8 and 40 °C, respectively. AgaWS5 showed a cold-tolerance, and it retained more than 40% of its maximum enzymatic activity at 10 °C. AgaWS5 is predicted to have several calcium-binding sites. Thus, its activity was slightly enhanced in the presence of Ca2+, and was strongly inhibited by EDTA. The Km and Vmax of AgaWS5 for agarose were 10.6 mg/mL and 714.3 U/mg, respectively. Agarose-liquefication, thin layer chromatography, and mass and NMR spectroscopic analyses demonstrated that AgaWS5 is an endo-type a-agarase that degrades agarose and mainly produces agarotetraose. Thus, in this study, a novel cold-adapted GH96 agarotetraose-producing a-agarase was identified.


April 21, 2020  |  

Potent LpxC Inhibitors with In Vitro Activity Against Multi-Drug Resistant Pseudomonas aeruginosa.

New drugs with novel mechanisms of resistance are desperately needed to address both community and nosocomial infections due to Gram-negative bacteria. One such potential target is LpxC, an essential enzyme that catalyzes the first committed step of Lipid A biosynthesis. Achaogen conducted an extensive research campaign to discover novel LpxC inhibitors with activity against Pseudomonas aeruginosa We report here the in vitro antibacterial activity and pharmacodynamics of ACHN-975, the only molecule from these efforts and the first ever LpxC inhibitor to be evaluated in Phase 1 clinical trials. In addition, we describe the profile of three additional LpxC inhibitors that were identified as potential lead molecules. These efforts did not produce an additional development candidate with a sufficiently large therapeutic window and the program was subsequently terminated.Copyright © 2019 American Society for Microbiology.


April 21, 2020  |  

Evolution of a 72-kb cointegrant, conjugative multiresistance plasmid from early community-associated methicillin-resistant Staphylococcus aureus isolates.

Horizontal transfer of plasmids encoding antimicrobial-resistance and virulence determinants has been instrumental in Staphylococcus aureus evolution, including the emergence of community-associated methicillin-resistant S. aureus (CA-MRSA). In the early 1990s the first CA-MRSA isolated in Western Australia (WA), WA-5, encoded cadmium, tetracycline and penicillin-resistance genes on plasmid pWBG753 (~30 kb). WA-5 and pWBG753 appeared only briefly in WA, however, fusidic-acid-resistance plasmids related to pWBG753 were also present in the first European CA-MRSA at the time. Here we characterized a 72-kb conjugative plasmid pWBG731 present in multiresistant WA-5-like clones from the same period. pWBG731 was a cointegrant formed from pWBG753 and a pWBG749-family conjugative plasmid. pWBG731 carried mupirocin, trimethoprim, cadmium and penicillin-resistance genes. The stepwise evolution of pWBG731 likely occurred through the combined actions of IS257, IS257-dependent miniature inverted-repeat transposable elements (MITEs) and the BinL resolution system of the ß-lactamase transposon Tn552 An evolutionary intermediate ~42-kb non-conjugative plasmid pWBG715, possessed the same resistance genes as pWBG731 but retained an integrated copy of the small tetracycline-resistance plasmid pT181. IS257 likely facilitated replacement of pT181 with conjugation genes on pWBG731, thus enabling autonomous transfer. Like conjugative plasmid pWBG749, pWBG731 also mobilized non-conjugative plasmids carrying oriT mimics. It seems likely that pWBG731 represents the product of multiple recombination events between the WA-5 pWBG753 plasmid and other mobile genetic elements present in indigenous CA-MSSA. The molecular evolution of pWBG731 saliently illustrates how diverse mobile genetic elements can together facilitate rapid accrual and horizontal dissemination of multiresistance in S. aureus CA-MRSA.Copyright © 2019 American Society for Microbiology.


April 21, 2020  |  

Resistome and a Novel blaNDM-1-Harboring Plasmid of an Acinetobacter haemolyticus Strain from a Children’s Hospital in Puebla, Mexico.

Acinetobacter calcoaceticus-baumannii complex isolates have been frequently associated with hospital and community infections, with A. baumannii being the most common. Other Acinetobacter spp. not belonging to this complex also cause infections in hospital settings, and the incidence has increased over the past few years. Some species of the Acinetobacter genus possess a great diversity of antibiotic resistance mechanisms, such as efflux pumps, porins, and resistance genes that can be acquired and disseminated by mobilizable genetic elements. By means of whole-genome sequencing, we describe in the clinical Acinetobacter haemolyticus strain AN54 different mechanisms of resistance that involve blaOXA-265, blaNDM-1, aphA6, aac(6′)-Ig, and a resistance-nodulation-cell division-type efflux pump. This strain carries six plasmids, of which the plasmid pAhaeAN54e contains blaNDM-1 in a Tn125-like transposon that is truncated at the 3′ end. This strain also has an insertion sequence IS91 and seven genes encoding hypothetical proteins. The pAhaeAN54e plasmid is nontypable and different from other plasmids carrying blaNDM-1 that have been reported in Mexico and other countries. The presence of these kinds of plasmids in an opportunistic pathogen such as A. haemolyticus highlights the role that these plasmids play in the dissemination of antibiotic resistance genes, especially against carbapenems, in Mexican hospitals.


April 21, 2020  |  

An Outbreak of KPC-Producing Klebsiella pneumoniae Linked with an Index Case of Community-Acquired KPC-Producing Isolate: Epidemiological Investigation and Whole Genome Sequencing Analysis.

Aims: A hospital outbreak of Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae (KPN) linked with an index case of community-acquired infection occurred in an urban tertiary care hospital in Seoul, South Korea. Therefore, we performed an outbreak investigation and whole genome sequencing (WGS) analysis to trace the outbreak and investigate the molecular characteristics of the isolates. Results: From October 2014 to January 2015, we identified a cluster of three patients in the neurosurgery ward with sputum cultures positive for carbapenem-resistant KPN. An epidemiological investigation, including pulsed-field gel electrophoresis analysis was performed to trace the origins of this outbreak. The index patient’s infection was community acquired. Active surveillance cultures using perirectal swabbing from exposed patients, identified one additional patient with KPC-producing KPN colonization. WGS analyses using PacBio RSII instruments were performed for four linked isolates. WGS revealed a genetic linkage of the four isolates belonging to the same sequence type (ST307). All KPN isolates harbored conjugative resistance plasmids, which has blaKPC-2 carbapenemase genes contained within the Tn4401 “a” isoform and other resistance genes. However, WGS showed only three isolates among four KPC-producing KPN were originated from a common origin. Conclusions: This report demonstrates the challenge that KPC-2-producing KPN with the conjugative resistance plasmid may spread not only in hospitals but also in community, and WGS can help to accurately characterize the outbreak.


April 21, 2020  |  

Complete genome sequence of Marinobacter sp. LQ44, a haloalkaliphilic phenol-degrading bacterium isolated from a deep-sea hydrothermal vent

Marinobacter sp. strain LQ44, an alkaliphile and moderate halophile from a deep-sea hydrothermal vent on the East Pacific Rise, is a novel phenol-degrading bacterium that is capable of utilizing phenol as sole carbon and energy sources. Here, we present the complete genome sequence of strain LQ44, which consists of 4,435,564?bp with a circular chromosome, 4164 protein-coding genes, 3 rRNA operons and 50 tRNAs. Genome analysis revealed that strain LQ44 may degrade phenol via meta-cleavage pathway. The LQ44 genome contains multiple genes involved in pH adaptation and osmotic adjustment. Genes related to hydrocarbon degradation, aerobic denitrification and potential industrial important enzymes were also identified from the genome. To our knowledge, this is the first report of a genome sequence of a haloalkaliphilic phenol-degrading bacterium, which will provide insights into the survival of this bacterium under salt-alkali conditions and the potential for biotechnological applications.


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