Biopreservation potential of enterococcus faecalis isolated from Italian traditional raw milk cheeses

Abstract

Enterococcus faecalis is frequently associated with raw milk cheeses of Mediterranean area. The genetic diversity of 38 E. faecalis obtained from raw milk products in Italy was assessed through Randomly Amplified Polymorphic DNA PCR (RAPD-PCR) and repetitive extragenic palindromic PCR (rep-PCR). The strains were screened for their antimicrobial activity against 5 food-borne spoilage and pathogenic bacteria and 13 lactic acid bacteria (LAB), commonly used as starter cultures. Investigation was made to identify the bacteriocinogenic potential by searching for bacteriocin-encoding genes. Inhibitory effects against undesirable bacteria, including Bacillus cereus (44.7% of strains), Escherichia coli (18.4%), Listeria monocytogenes (15.8%), Staphylococcus aureus (2.6%), and Clostridium sporogenes (21.1%), were detected. Moderate antagonism towards LAB was found. One strain producing enterocin AS-48 was identified, suggesting that the antimicrobial activity of the phenotypically positive isolates should be necessarily due to another non-enterocin factor. A deeper insight into biopreservation potential of dairy E. faecalis was provided, highlighting the influence of this species on cheese microbial community. © 2013 Taylor & Francis.