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July 7, 2019

Paenibacillus larvae-directed bacteriophage HB10c2 and its application in American Foulbrood-affected honey bee larvae.

Paenibacillus larvae is the causative agent of American foulbrood (AFB), the most serious honey bee brood bacterial disease. We isolated and characterized P. larvae-directed bacteriophages and developed criteria for safe phage therapy. Whole-genome analysis of a highly lytic virus of the family Siphoviridae (HB10c2) provided a detailed safety profile and uncovered its lysogenic nature and a putative beta-lactamase-like protein. To rate its antagonistic activity against the pathogens targeted and to specify potentially harmful effects on the bee population and the environment, P. larvae genotypes ERIC I to IV, representatives of the bee gut microbiota, and a broad panel of members of the order Bacillales were analyzed for phage HB10c2-induced lysis. Breeding assays with infected bee larvae revealed that the in vitro phage activity observed was not predictive of the real-life scenario and therapeutic efficacy. On the basis of the disclosed P. larvae-bacteriophage coevolution, we discuss the future prospects of AFB phage therapy. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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July 7, 2019

Genome architecture of Lactobacillus plantarum PS128, a probiotic strain with potential immunomodulatory activity.

Clinical and preclinical observations indicate that Lactobacillus plantarum has anti-inflammatory activity and may regulate the immune responses of its hosts when ingested. Recently, modification of teichoic acids (TAs) produced by L. plantarum was reported as a key to regulating the systemic immune response in mice. However, data linking TA-related genetic determinants and the immunomodulatory effect are limited. To provide genomic information for elucidating the underlying mechanism of immunomodulation by L. plantarum, we sequenced the genome of L. plantarum strain PS128.The PS128 genome contains 11 contigs (3,325,806 bp; 44.42% GC content) after hybrid assembly of sequences derived with Illumina MiSeq and PacBio RSII systems. The most abundant functions of the protein-coding genes are carbohydrate, amino acid, and protein metabolism. The 16S rDNA sequences of PS128 are closest to the sequences of L. plantarum WCFS1 and B21; these three strains form a distinct clade based on 16S rDNA sequences. PS128 shares core genes encoding the metabolism, transport, and modification of TAs with other sequenced L. plantarum strains. Compared with the TA-related genes of other completely sequenced L. plantarum strains, the PS128 contains more lipoteichoic acid exporter genes.We determined the draft genome sequence of PS128 and compared its TA-related genes with those of other L. plantarum strains. Shared genomic features with respect to TA-related subsystems may be important clues to the mechanism by which L. plantarum regulates its host immune responses, but unique TA-related genetic determinants should be further investigated to elucidate strain-specific immunomodulatory effects.

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July 7, 2019

Complete genome sequence of Lactobacillus paracasei CAUH35, a new strain isolated from traditional fermented dairy product koumiss in China.

Lactobacillus paracasei CAUH35 was isolated from homemade koumiss, a traditional fermented dairy product with beneficial effects on human health. The genome consists of a circular 2,770,411bp chromosome and four plasmids. Genome analysis revealed the presence of gene clusters involved in the production of exopolysaccharides and bacteriocin. The complete genome sequence of L. paracasei CAUH35 will provide genetic basis for further comparative and functional genomic analyses. Copyright © 2015. Published by Elsevier B.V.

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July 7, 2019

Complete genome sequence of Lactobacillus paracasei L9, a new probiotic strain with high lactic acid-producing capacity.

Lactobaillus paracasei L9 (CGMCC No. 9800) is a new strain with probiotic properties originating from healthy human intestine. Previous studies evidenced that the strain regulates immune modulation and contributes to the production of high amounts of lactic acid. The genome of L. paracasei L9 contains a circular 3076,437-bp chromosome, encoding 3044 CDSs, 15 rRNA genes and 59 tRNA genes. Copyright © 2015. Published by Elsevier B.V.

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July 7, 2019

Complete genome sequence of Lactobacillus heilongjiangensis DSM 28069(T): Insight into its probiotic potential.

Lactobacillus heilongjiangensis DSM 28069(T) is a potential probiotic isolated from traditional Chinese pickle. Here we report the complete genome sequence of this strain. The complete genome is 2,790,548bp with the GC content of 37.5% and devoid of plasmids. Sets of genes involved in the biosynthesis of riboflavin and folate were identified in the genome, which revealed its potential application in biotechnological industry. The genome sequence of L. heilongjiangensis DSM 28069(T) now provides the fundamental information for future studies. Copyright © 2015. Published by Elsevier B.V.

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July 7, 2019

Complete genome sequence of Enterococcus durans KLDS6.0930, a strain with probiotic properties.

Enterococcus durans KLDS6.0930 strain was originally isolated from traditional naturally fermented cream in Inner Mongolia of China. The complete genome sequence of E. durans KLDS6.0930 was carried out using the PacBio RSII platform. The genome contains a circular chromosome and two circular plasmids. Genome sequencing information provides the genetic basis for bioinformatics analysis of bile salt and acid tolerance, cell adhesion, and molecular mechanisms responsible for lipid metabolism. Copyright © 2015 Elsevier B.V. All rights reserved.

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July 7, 2019

Global insights into acetic acid resistance mechanisms and genetic stability of Acetobacter pasteurianus strains by comparative genomics.

Acetobacter pasteurianus (Ap) CICC 20001 and CGMCC 1.41 are two acetic acid bacteria strains that, because of their strong abilities to produce and tolerate high concentrations of acetic acid, have been widely used to brew vinegar in China. To globally understand the fermentation characteristics, acid-tolerant mechanisms and genetic stabilities, their genomes were sequenced. Genomic comparisons with 9 other sequenced Ap strains revealed that their chromosomes were evolutionarily conserved, whereas the plasmids were unique compared with other Ap strains. Analysis of the acid-tolerant metabolic pathway at the genomic level indicated that the metabolism of some amino acids and the known mechanisms of acetic acid tolerance, might collaboratively contribute to acetic acid resistance in Ap strains. The balance of instability factors and stability factors in the genomes of Ap CICC 20001 and CGMCC 1.41 strains might be the basis for their genetic stability, consistent with their stable industrial performances. These observations provide important insights into the acid resistance mechanism and the genetic stability of Ap strains and lay a foundation for future genetic manipulation and engineering of these two strains.

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July 7, 2019

First genome sequences of Achromobacter phages reveal new members of the N4 family.

Multi-resistant Achromobacter xylosoxidans has been recognized as an emerging pathogen causing nosocomially acquired infections during the last years. Phages as natural opponents could be an alternative to fight such infections. Bacteriophages against this opportunistic pathogen were isolated in a recent study. This study shows a molecular analysis of two podoviruses and reveals first insights into the genomic structure of Achromobacter phages so far.Growth curve experiments and adsorption kinetics were performed for both phages. Adsorption and propagation in cells were visualized by electron microscopy. Both phage genomes were sequenced with the PacBio RS II system based on single molecule, real-time (SMRT) technology and annotated with several bioinformatic tools. To further elucidate the evolutionary relationships between the phage genomes, a phylogenomic analysis was conducted using the genome Blast Distance Phylogeny approach (GBDP).In this study, we present the first detailed analysis of genome sequences of two Achromobacter phages so far. Phages JWAlpha and JWDelta were isolated from two different waste water treatment plants in Germany. Both phages belong to the Podoviridae and contain linear, double-stranded DNA with a length of 72329 bp and 73659 bp, respectively. 92 and 89 putative open reading frames were identified for JWAlpha and JWDelta, respectively, by bioinformatic analysis with several tools. The genomes have nearly the same organization and could be divided into different clusters for transcription, replication, host interaction, head and tail structure and lysis. Detailed annotation via protein comparisons with BLASTP revealed strong similarities to N4-like phages.Analysis of the genomes of Achromobacter phages JWAlpha and JWDelta and comparisons of different gene clusters with other phages revealed that they might be strongly related to other N4-like phages, especially of the Escherichia group. Although all these phages show a highly conserved genomic structure and partially strong similarities at the amino acid level, some differences could be identified. Those differences, e.g. the existence of specific genes for replication or host interaction in some N4-like phages, seem to be interesting targets for further examination of function and specific mechanisms, which might enlighten the mechanism of phage establishment in the host cell after infection.

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July 7, 2019

Complete genome sequence of Enterococcus mundtii QU 25, an efficient L-(+)-lactic acid-producing bacterium.

Enterococcus mundtii QU 25, a non-dairy bacterial strain of ovine faecal origin, can ferment both cellobiose and xylose to produce l-lactic acid. The use of this strain is highly desirable for economical l-lactate production from renewable biomass substrates. Genome sequence determination is necessary for the genetic improvement of this strain. We report the complete genome sequence of strain QU 25, primarily determined using Pacific Biosciences sequencing technology. The E. mundtii QU 25 genome comprises a 3 022 186-bp single circular chromosome (GC content, 38.6%) and five circular plasmids: pQY182, pQY082, pQY039, pQY024, and pQY003. In all, 2900 protein-coding sequences, 63 tRNA genes, and 6 rRNA operons were predicted in the QU 25 chromosome. Plasmid pQY024 harbours genes for mundticin production. We found that strain QU 25 produces a bacteriocin, suggesting that mundticin-encoded genes on plasmid pQY024 were functional. For lactic acid fermentation, two gene clusters were identified-one involved in the initial metabolism of xylose and uptake of pentose and the second containing genes for the pentose phosphate pathway and uptake of related sugars. This is the first complete genome sequence of an E. mundtii strain. The data provide insights into lactate production in this bacterium and its evolution among enterococci. © The Author 2014. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

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July 7, 2019

Safety of the surrogate microorganism Enterococcus faecium NRRL B-2354 for use in thermal process validation.

Enterococcus faecium NRRL B-2354 is a surrogate microorganism used in place of pathogens for validation of thermal processing technologies and systems. We evaluated the safety of strain NRRL B-2354 based on its genomic and functional characteristics. The genome of E. faecium NRRL B-2354 was sequenced and found to comprise a 2,635,572-bp chromosome and a 214,319-bp megaplasmid. A total of 2,639 coding sequences were identified, including 45 genes unique to this strain. Hierarchical clustering of the NRRL B-2354 genome with 126 other E. faecium genomes as well as pbp5 locus comparisons and multilocus sequence typing (MLST) showed that the genotype of this strain is most similar to commensal, or community-associated, strains of this species. E. faecium NRRL B-2354 lacks antibiotic resistance genes, and both NRRL B-2354 and its clonal relative ATCC 8459 are sensitive to clinically relevant antibiotics. This organism also lacks, or contains nonfunctional copies of, enterococcal virulence genes including acm, cyl, the ebp operon, esp, gelE, hyl, IS16, and associated phenotypes. It does contain scm, sagA, efaA, and pilA, although either these genes were not expressed or their roles in enterococcal virulence are not well understood. Compared with the clinical strains TX0082 and 1,231,502, E. faecium NRRL B-2354 was more resistant to acidic conditions (pH 2.4) and high temperatures (60°C) and was able to grow in 8% ethanol. These findings support the continued use of E. faecium NRRL B-2354 in thermal process validation of food products.

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July 7, 2019

Complete genome sequence of the Gram-negative probiotic Escherichia coli strain Nissle 1917.

Escherichia coli strain Nissle 1917 (EcN) is the active principle of a probiotic preparation (trade name Mutaflor(®)) used for the treatment of patients with intestinal diseases such as ulcerative colitis and diarrhea. It has GRAS (generally recognized as save) status and has been shown to be a therapeutically effective drug (Sonnenborn and Schulze, 2009). The complete genomic DNA sequence will help in identifying genes and their products which are essential for the strains probiotic nature. Genbank/EMBL/DDBJ accession number: CP007799 (chromosome). Copyright © 2014 Elsevier B.V. All rights reserved.

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July 7, 2019

Complete genome sequence of the cyanide-degrading bacterium Pseudomonas pseudoalcaligenes CECT5344.

Pseudomonas pseudoalcaligenes CECT5344, a Gram-negative bacterium isolated from the Guadalquir River (Córdoba, Spain), is able to utilize different cyano-derivatives. Here, the complete genome sequence of P. pseudoalcaligenes CECT5344 harboring a 4,686,340bp circular chromosome encoding 4513 genes and featuring a GC-content of 62.34% is reported. Necessarily, remaining gaps in the genome had to be closed by assembly of few long reads obtained from PacBio single molecule real-time sequencing. Here, the first complete genome sequence for the species P. pseudoalcaligenes is presented. Copyright © 2014 Elsevier B.V. All rights reserved.

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July 7, 2019

Quality scores for 32,000 genomes.

More than 80% of the microbial genomes in GenBank are of ‘draft’ quality (12,553 draft vs. 2,679 finished, as of October, 2013). We have examined all the microbial DNA sequences available for complete, draft, and Sequence Read Archive genomes in GenBank as well as three other major public databases, and assigned quality scores for more than 30,000 prokaryotic genome sequences.Scores were assigned using four categories: the completeness of the assembly, the presence of full-length rRNA genes, tRNA composition and the presence of a set of 102 conserved genes in prokaryotes. Most (~88%) of the genomes had quality scores of 0.8 or better and can be safely used for standard comparative genomics analysis. We compared genomes across factors that may influence the score. We found that although sequencing depth coverage of over 100x did not ensure a better score, sequencing read length was a better indicator of sequencing quality. With few exceptions, most of the 30,000 genomes have nearly all the 102 essential genes.The score can be used to set thresholds for screening data when analyzing “all published genomes” and reference data is either not available or not applicable. The scores highlighted organisms for which commonly used tools do not perform well. This information can be used to improve tools and to serve a broad group of users as more diverse organisms are sequenced. Unexpectedly, the comparison of predicted tRNAs across 15,000 high quality genomes showed that anticodons beginning with an ‘A’ (codons ending with a ‘U’) are almost non-existent, with the exception of one arginine codon (CGU); this has been noted previously in the literature for a few genomes, but not with the depth found here.

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