Abstract:

This study analyzed the bacteriocin-producing capability of 39 lactic acid bacteria strains isolated from yak
cheeses collected from Tibet, Xinjiang and Yunnan province of China. The crude extracts rich in bacteriocin were prepared.
Agar well-diffusion method was used to test their bacteriostatic activities against 9 pathogenic reference strains (Bacillus
cereus, Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes, Citrobacterfreundii, Salmonella
typhimurium, Enterobacter cloacae, Clostridium perfringens, and Bacterium sonnei) as well as 2 non-pathogenic reference
strains (Listeria monocytogenes and Streptococcus thermophilus). The crude extracts of 30 out of the 39 stains exhibited
bacteriostatic activities against these reference strains. Three strains, namely Y13, X29 and X30, were selected as excellent
bacteriocin-producing strains with a broad antimicrobial spectrum. They hold promise for potential applications in the
prevention and control of food-borne pathogenic bacteria.

Key words: lactic acid bacteria, yak cheese, bacteriocin, pathogenic strain