Genetic relationships among Enterococcus faecalis isolates from different sources as revealed by multilocus sequence typing

Abstract

Enterococcus faecalis is part of the natural gut flora of humans and other mammals; some isolates are also used in food production. So, it is important to evaluate the genetic diversity and phylogenetic relationships among E. faecalis isolates from different sources. Multilocus sequence typing protocol was used to compare 39 E. faecalis isolates from Chinese traditional food products (including dairy products, acidic gruel) and 4 published E. faecalis isolates from other sources including human-derived isolates employing 5 housekeeping genes (groEL, clpX, recA, rpoB, and pepC). A total of 23 unique sequence types were identified, which were grouped into 5 clonal complexes and 10 singletons. The value of standardized index of association of the alleles (IA(S)=0.1465) and network structure indicated a high frequency of intraspecies recombination across these isolates. Enterococcus faecalis lineages also exhibited clearly source-clustered distributions. The isolates from dairy source were clustered together. However, the relationship between isolates from acidic gruel and one isolate from a human source was close. The MLST scheme presented in this study provides a sharable and continuously growing sequence database enabling global comparison of strains from different sources, and will further advance our understanding of the microbial ecology of this important species.

In vitro characterisation of probiotic properties of Enterococcus faecium and Enterococcus durans strains isolated from raw milk and traditional dairy products

“…Unlike other lactic acid bacteria, enterococci are not considered GRAS (generally regarded as safe), and their presence in water is considered an indicator of faecal contamination. However, enterococci are important lactic acid bacteria in the fermented food industry due to their probiotic properties and ability to synthesise proteins with antimicrobial activity such as bacteriocin production (Klein ; Chen et al ). In addition, the use of Enterococcus strains with probiotic properties as food additives has been proposed in the International Meeting of Lactic Acid Bacteria Industrial Platform (Robinson ).…”

Comparative genomic analysis of Enterococcus faecalis: insights into their environmental adaptations

“…As a species of lactic acid bacteria, E. faecalis is widely used in the production of fermented foods, particularly fermented dairy products. In recent years, numerous E. faecalis strains have been recovered from traditional dairy products [ 10 – 13 ]. Furthermore, water and soil are also common habitats of E. faecalis [ 14 – 16 ].…”

Molecular Identification of Lactic Acid Bacteria Isolated from the Traditional Fermented Yak Yogurt in Western Sichuan Region

“…Similar to other bacteria, lactic acid bacteria exchange genetic materials from the environment through horizontal gene transfer to adapt to the new environment and to survive. Chen et al [22] proposed that Enterococcus faecium in the natural fermented milk of different resources evolved to adapt to the environment. Zhang et al [23] found in the study to genetic diversity of Leuconostoc mesenteroides that isolated strains had rich genetic diversity.…”