Isolation of Lactic Acid Bacteria with High-yield Bacteriocin from Fermented Grians of Light-flavor Baijiu and Its Bacteriocin Characteristic

Objective:To isolate high-yield bacteriocin-producing lactic acid bacteria from fermented grains of light-flavor Baijiu brewing,and analyze the possibility of its application in light-flavor Baijiu brewing. Methods:Lactic acid bacteria with bacteriostatic activity were isolated by Oxford cup method,and identified by 16S rDNA method combined morphology. The stability of their bacteriocins and their influence on the brewing microorganisms were studied. Results:From 146 Lactobacillus strains,four strains had obvious inhibitory effects on indicator strains(Staphylococcus aureus,Escherichis coli,Bacillus subtilis). Among the four strains,YP36 was identified as Lactobacillus plantarum,MC15-1 and MC49-1 as Lactobacillus brevis,and SL28 as Lactobacillus buchneri. On the stability of bacteriocin,the bacteriocins of YP36 and SL28 had no significant change in the range of 4~121℃(P>0.05),and the bacteriocins of MC15-1 and MC49-1 were stable in the range of 4~60℃(P>0.05),and the antibacterial activity after treatment at 121℃ was to 68.4% and 56.38% at 4℃,respectively. pH stability of the bacteriocins from the four strains were very similar,and there was no significant change in bacteriostatic activity(P>0.05)in the range of pH2.0~4.0,which decreased slightly when pH was 6.0,and disappeared when pH was 8.0. The bacteriocins of the four strains had no inhibitory effect on the yeasts appeared in fermented grains of light-flavor brewing.The results showed that strains YP36,MC15-1,SL28 and MC49-1 had better physical and chemical properties,which was of great significance for the application of lactic acid bacteria in the fermented grains.