Enterocin HZ produced by a wildEnterococcus faeciumstrain isolated from a traditional, starter-free pickled cheese

Abstract

BacteriogenicEnterococcus faeciumHZ was identified by using biochemical (Strep-API 20, API-50 CHL, fatty acid profile) and 16S rRNA analysis (99·99 %).Ent. faeciumHZ was sensitive to clinically important antibiotics such as vancomycin, and did not have gelatinase and haemolysis activities. Enterocin HZ, a bacteriocin fromEnt. faeciumHZ, was sensitive to papain and tyripsin, but resistant to pepsin, lipase, catalase, α-amylase, organic solvents, detergents, ß-mercaptoethanol, and heat treatment (90 °C/30 min). It was biologically active at pH 2·0–9·0 and synthesised at the highest level in MRS or M17 broth at 32 or 37 °C with an inoculum amount of 0·1–0·5 % and an initial pH of 6·0–7·0. Enterocin HZ production reached maximum level at middle and late logarithmic phase and its molecular weight was ∼4·5 kDa. It was active against some Gram-positive foodborne bacteria.Ent. faeciumHZ or its bacteriocin enterocin HZ is a good candidate to be studied as a food biopreservative since enterocin HZ showed strong bactericidal activity againstListeria monocytogenesin UHT milk and alsoEnt. faeciumHZ grew very well in milk and produced enterocin HZ at maximum level.