Department of Microbiology and Biotechnology, 14878Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Hermann-Weigmann-Str. 1, 24103 Kiel, Germany.
Research Group of Industrial Microbiology and Food Biotechnology (IMDO), Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
Benef Microbes. 2024 Mar 11;15(2):211-225. doi: 10.1163/18762891-bja00005.
Enterococcus faecium SF68 (SF68) is a well-known probiotic with a long history of safe use. Recent changes in the taxonomy of enterococci have shown that a novel species, Enterococcus lactis, is closely related with E. faecium and occurs together with other enterococci in a phylogenetically well-defined E. faecium species group. The close phylogenetic relationship between the species E. faecium and E. lactis prompted a closer investigation into the taxonomic status of E. faecium SF68. Using phylogenomics and ANI, the taxonomic analysis in this study showed that probiotic E. faecium SF68, when compared to other E. faecium and E. lactis type and reference strains, could be re-classified as belonging to the species E. lactis. Further investigations into the functional properties of SF68 showed that it is potentially capable of bacteriocin production, as a bacteriocin gene cluster encoding the leaderless bacteriocin EntK1 together with putative Lactococcus lactis bacteriocins LsbA, and LsbB-like putative immunity peptide (LmrB) were found located in an operon on plasmid pF9. However, bacteriocin expression was not studied. Competitive exclusion experiments in co-culture over 7 days at 37 °C showed that the probiotic SF68 could inhibit the growth of specific E. faecium and Listeria monocytogenes strains, while showing little or no inhibitory activity towards an entero-invasive Escherichia coli and a Salmonella Typhimurium strain, respectively. In cell culture experiments with colon carcinoma HT29 cells, the probiotic SF68 was also able to strain-specifically inhibit adhesion and/or invasion of enterococcal and L. monocytogenes strains, while such adhesion and invasion inhibition effects were less pronounced for E. coli and Salmonella strains. This study therefore provides novel data on the taxonomy and functional properties of SF68, which can be reclassified as Enterococcus lactis SF68, thereby enhancing the understanding of its probiotic nature.
屎肠球菌 SF68（SF68）是一种众所周知的益生菌，具有悠久的安全使用历史。最近肠球菌分类学的变化表明，一种新型物种， Lactococcus lactis ，与屎肠球菌密切相关，并且与其他肠球菌一起存在于一个系统发育上明确定义的屎肠球菌物种群中。物种屎肠球菌和 Lactococcus lactis 之间的密切亲缘关系促使人们更深入地研究益生菌屎肠球菌 SF68 的分类地位。使用系统基因组学和 ANI，本研究的分类分析表明，与其他屎肠球菌和 Lactococcus lactis 型和参考菌株相比，益生菌屎肠球菌 SF68 可以重新归类为 Lactococcus lactis 。进一步研究 SF68 的功能特性表明，它可能具有细菌素产生能力，因为编码无领导细菌素 EntK1 的细菌素基因簇与推定的乳球菌细菌素 LsbA 和 LsbB 样推定免疫肽（LmrB）一起位于质粒 pF9 上的操纵子中。然而，没有研究细菌素表达。在 37°C 下共培养 7 天的竞争排除实验表明，益生菌 SF68 可以抑制特定屎肠球菌和单核细胞李斯特菌菌株的生长，而对肠侵袭性大肠杆菌和沙门氏菌 Typhimurium 菌株的抑制活性较小或没有。在结肠癌细胞 HT29 细胞的细胞培养实验中，益生菌 SF68 还能够特异性抑制肠球菌和单核细胞李斯特菌菌株的粘附和/或侵袭，而对大肠杆菌和沙门氏菌菌株的粘附和侵袭抑制作用则不那么明显。因此，本研究提供了 SF68 的分类学和功能特性的新数据，SF68 可重新归类为 Lactococcus lactis SF68 ，从而增强对其益生菌特性的理解。
