Enterococcus faecium LM-2, a multi-bacteriocinogenic strain naturally occurring in "Byaslag", a traditional cheese of Inner Mongolia in China

A bacteriocin-producing strain LM-2 was isolated from Byaslag a traditional cheese in Inner Mongolia of China and identified as Enterococcus faecium The strain produced the maximum activity of enterocin (5120 AU ml(-1)) in MRS medium in the mid-stationary phase of growth (ie after 30 h at 37 C) Purified enterocin LM-2 was obtained by using a two-step procedure consisting of ammonium sulfate precipitation and cation exchange chromatography Triune-SOS-PAGE of the purified entertiocin LM-2 contained two active protein bands between 35 and 64 kDa It showed a broad spectrum of activity against most of the tested strains in the genera Listeria Staphylococcus Bacillus Clostridium Salmonella and Pseudomonas All Listeria strains tested including L monocyiogenes were highly sensitive to this bacteriocin The inhibitory activity of enterocin LM-2 against I monocytogenes was bactericidal without concomitant cell growth and the highest level of adsorption (87 5%) to the surface of L monocytogenes 54002 cells was founded at pH 60 This strong inhibitory activity against L monocytogenes coupled with its broad pH-resistance and heat-stability indicated its potential use as a food preservative to enhance the safety of fermented foods The presence of enterocin P and L5O-like structural genes in E faecium LM-2 was established by PCR and direct sequencing which indicated strain LM-2 may be a new multi-bacteriocin producer strain (C) 2010 Elsevier Ltd All rights reserved