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.