Enterocin HZ produced by a wild Enterococcus faecium strain isolated from a traditional, starter-free pickled cheese

摘要

Bacteriogenic Enterococcus faecium HZ was identified by using biochemical (Strep-API 20, API-50 CHL, fatty acid profile) and 16S rRNA analysis (99-99 %). Ent. faecium HZ was sensitive to clinically important antibiotics such as vancomycin, and did not have gelatinase and haemolysis activities. Enterocin HZ, a bacteriocin from Ent. faecium HZ, was sensitive to papain and tyripsin, but resistant to pepsin, lipase, catalase, α-amylase, organic solvents, detergents, β-mercaptoethanol, and heat treatment (90℃/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 ℃ 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. faecium HZ or its bacteriocin enterocin HZ is a good candidate to be studied as a food biopreservative since enterocin HZ showed strong bactericidal activity against Listeria mono-cytogenes in UHT milk and also Ent. faecium HZ grew very well in milk and produced enterocin HZ at maximum level.