Genomic analysis of Enterococcus durans LAB18S, a potential probiotic strain isolated from cheese

Abstract Gut microbiota exerts a fundamental role in human health and increased evidence supports the beneficial role of probiotic microorganisms in the maintenance of intestinal health. Enterococcus durans LAB18S was previously isolated from soft cheese and showed some desirable in vitro probiotic properties, for that reason its genome was sequenced and evaluated for genes that can be relevant for probiotic activity and are involved in selenium metabolism. Genome sequencing was performed using the Illumina MiSeq System. A variety of genes potentially associated with probiotic properties, including adhesion capability, viability at low pH, bile salt resistance, antimicrobial activity, and utilization of prebiotic fructooligosaccharides (FOS) were identified. The strain showed tolerance to acid pH and bile salts, exhibited antimicrobial activity and thrived on prebiotic oligosaccharides. Six genes involved in selenium metabolism were predicted. Analysis of the SECIS element showed twelve known selenoprotein candidates. E. durans LAB18S was the only food isolate showing absence of plasmids, virulence and antimicrobial resistance genes, when compared with other 30 E. durans genomes. The results of this study provide evidence supporting the potential of E. durans LAB18S as alternative for probiotic formulations.

摘要：肠道菌群（gut microbiota）在人类健康中发挥着基础性作用，日益增多的研究证据证实了益生菌在维持肠道健康方面的有益功效。耐久肠球菌（Enterococcus durans）LAB18S此前从软质奶酪中分离得到，且展现出若干理想的体外益生菌特性。据此，研究人员对其基因组进行了测序，并针对与益生菌活性相关、参与硒代谢的基因展开了评估。基因组测序采用Illumina MiSeq测序系统完成。研究鉴定出多种与益生菌特性潜在相关的基因，包括黏附能力、低pH耐受性、胆盐抗性、抗菌活性以及益生元低聚果糖（fructooligosaccharides, FOS）的利用相关基因。该菌株对酸性pH环境及胆盐具有耐受性，展现出抗菌活性，且可在益生元寡糖环境中良好生长。研究预测出6个参与硒代谢的基因。对SECIS元件（SECIS element）的分析显示存在12个已知的硒蛋白候选体。相较于其他30株耐久肠球菌的基因组，耐久肠球菌LAB18S是唯一一株未携带质粒、毒力基因及抗菌耐药基因的食品分离菌株。本研究结果证实，耐久肠球菌LAB18S具备开发为益生菌制剂替代品的潜力。