Biochemical and antimicrobial profile ofEnterococcus faeciumandE. faecalisisolated from traditional dairy products and infant intestinal microbiota

Abstract

Background: Unpasteurized fermented milk is used for the production of traditional dairy products in certain rural areas of Greece. Methods: In an attempt to search for candidate benefi cial probiotic strains of Enterococcus faecium and Enterococcus faecalis, isolates recovered from traditional dairy products and from faeces of infants fed with such products were evaluated regarding their antimicrobial activity and their standard biochemical profi le. Results: Almost all tested strains showed resistance to a pH range from 3.0 to 6.5, tolerance to bile acid within 24 h and resistance to phenol. Field isolates of E. faecalis and E. faecium presented higher antimicrobial activity against classic food pathogenic serovars of Salmonella enteritica (S. typhi, S. typhimurium, S. ancona, S. enteritidis) compared with reference strains. Conclusion: The implementation of benefi cial enterococcal strains in the production of fermented dairy products is part of technological process in constant development aimed at obtaining food products of increased quality and safety.

Antibiotic susceptibility, antibacterial activity and characterisation of Enterococcus faecium strains isolated from breast milk

“…Conversely, an acidifying potential was demonstrated for E. faecium strains isolated from bovine milk; the pH of MRS broth was lowered to ~3.85–4.05 following incubation for 48 h ( 26 ). In the present study, the Enterococci isolates were resistant to bile acid following exposure for 24 h, which is consistent with a previous study ( 28 ). This resistance may be due to the inactivation of various bile components by β-glucuronidase activity.…”

“…Lysozyme promotes the hydrolysis of the bacterial cell ( 29 ). The E. faecium strains isolated in the present study exhibited resistance to lysozyme-mediated hydrolysis, which is consistent with a previous study ( 28 ).…”

“…These findings are in agreement with a previous study ( 23 ). In addition, E. faecium has been shown to exhibit high acid resistance at pH 2.0 and 1.0 ( 28 ); however, in the present study, the E. faecium strains were susceptible to acid at pH 1.0, which is consistent with a previous study ( 28 ).…”

“…In the presence of 0.4% phenol, E. faecium strains did not grow following incubation for 24 h. In a previous study, Enterococci strains exhibited a high resistance to phenol ( 28 ). Lysozyme promotes the hydrolysis of the bacterial cell ( 29 ).…”

Probiotics in Medicine: A Long Debate

“…Moreover, probiotics are known to have particular properties such as; resistance to acid pH, bile tolerance, tolerance to pancreatic fluid, adhesion and invasion capacity in the intestinal epithelial cells (2). The above properties permit their survival in the gastrointestinal tract and the improvement of the intestinal balance (2).…”