Biological Characterization of Bacteriocin Produced by Cold-Adapted Enterococcus sp. MB2-1

DENG Mei;WANG Jun-gang;GAO Yang;NI Yong-qing;College of Food Science,Shihezi University;Agricultural Product Processing Research Institute,Xinjiang Academy of Agricultural and Reclamation Science;

psychrotrophs;;Enterococcus;;bacteriocin;;16S rRNA gene;;antimicrobial activity

Strain MB2-1, isolated from the intestine of cold-water fish from Erqisi River in Aletai, Xinjiang, was able to produce a cold-active bacteriocin with inhibitory activity against several food spoilage bacteria and foodborne pathogens, including the Gram-positive bacteria Listeria monocytogenes, Staphylococcus aureus and Bacillus subtilis and the Gramnegative bacterium Escherichia coli. Strain MB2-1 was identified as Enterococcus spp. by using both phenotypical test and 16S rRNA gene sequence analysis. This strain showed the optimal growth temperature ranging from 20 to 24 ℃. The bacteriocin produced by it, designated enterocin MB2-1, was sensitive to proteolytic enzymes. Enterocin MB2-1 exhibited strong thermal stability(60 min at 100 ℃) and pH stability(pH 3.0 to 9.0). In addition, enterocin MB2-1 was not inactivated when treated with catalase, TritonX-100, SDS, Tween-80, NaCl or EDTA. The production of enterocin MB2-1 started at the early exponential phase(approximately to 9 h) and reached its maximum level at the early stationary phase(33 h). These characteristics suggest that enterocin MB2-1 has potential applications in food preservation. The safety aspects of strain MB2-1 need to be further explored in order to evaluate their potentials for biotechnological applications.