Complete genome sequences of two Enterococcus faecium strains and comparative genomic analysis.

Enterococci are used for improvement of the intestinal environment and have clinical benefits. Enterococcus faecalis and Enterococcus faecium have similar morphologies, leading to confusion between the two species. In order to identify the National Institute for Food and Drug Control (strain 140623) and Shin Biofermin S (strain SBS-1, one of the cocci), which are widely used clinically, the present study sequenced and analyzed these two strains. The biochemical characteristics, gas chromatography and mass spectrometry results of 140623 and SBS-1 revealed that the two strains were more similar to E. faecium than E. faecalis. The genomes of 140623 and SBS-1 contained 2,812,926 bp and 2,797,745 bp, respectively, based on Illumina HiSeq 2000 sequencing. Phylogenetic analysis demonstrated that 140623 and SBS-1 belonged to the phylogenetic group of E. faecium. The Gene Ontology, Kyoto Encyclopedia of Genes and Genomes and Clusters of Orthologous Groups classifications of the two sequenced genomes were highly conserved with reference to E. faecium strains. A total of 6 putative virulence-associated genes, 15 antibiotic resistance genes and 31 genes associated with bacterial toxins were identified from 140623 and SBS-1, representing their resistance mechanisms in natural environments and their potential for clinical use in food and drug safety.

[Analysis of microbial community of heat resistant microorganisms in Chinese herbal pieces].

To investigate the composition and diversity of heat resistant microorganisms in contaminated Chinese herbal pieces. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) protein fingerprinting and 16S rRNA high-throughput sequencing of Illumina Miseq were used to analyze the heat resistant microbial community of 9 varieties of Chinese herbal pieces. Stem pieces (Spatholobi Caulis, Tetrapanacis Medulla, Stachyuri Medulla) showed highest detection rate and most species of contaminants; However fruit pieces (Schisandrae Sphenantherae Fructus) had the lowest detection rate and least species of contaminants; among root pieces, the detection rate and number of contaminants species were lower in Tuber Dioscoreae Persimilis and Rehmanniae Radix Praeparata. The heat resistant microbial community was mainly of Bacillaceae and Paenibacillaceae, and Bacillus showed the highest detection rate among them, followed by Brevibacillus, Paenibacillus, and Solibacillus. The rest genus in high-throughput sequencing analysis included Enterobacter, Brevundimonas, Leuconostoc, Methylobacterium, Dechloromonas, Pantoea, Klebsiella, and Erwinia. There were potential risk factors in heat resistant microbial community of Chinese herbal pieces, so we shall improve the microbial limit standard, strictly control the pathogenic bacteria in the product, and strengthen the supervision and management in production and circulation of Chinese herbal pieces.

Requirement of a mip-like gene for virulence in the phytopathogenic bacterium Xanthomonas campestris pv. campestris.

Macrophage infectivity potentiators (Mips) are FKBP domain-containing proteins reported as virulence factors in several human pathogens, such as members of genera Legionella, Salmonella and Chlamydia. The putative peptidylprolyl cis-trans isomerase (PPIase) encoded by XC2699 of the plant bacterial pathogen Xanthomonas campestris pv. campestris 8004 exhibits a 49% similarity at the amino-acid level to the Mip protein of Legionella pneumophila. This mip-like gene, XC2699, was overexpressed in Escherichia coli and the purified (His)6-tagged Mip-like protein encoded by XC2699 exhibited a PPIase activity specifically inhibited by FK-506. A mutation in the mip-like gene XC2699 led to significant reductions in virulence and replication capacity in the host plant Chinese radish (Raphanus sativus L. var. radiculus Pers.). Furthermore, the production of exopolysaccharide and the activity of extracellular proteases, virulence factors of X. campestris pv. campestris, were significantly decreased in the mip-like mutant. These results reveal that the mip-like gene is involved in the pathogenesis of X. campestris pv. campestris through an effect on the production of these virulence factors.