Abstract:

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 MB2-1was 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.

Key words: psychrotrophs, Enterococcus, bacteriocin, 16S rRNA gene, antimicrobial activity