Screening Of The Bacteriocin-producing Lactic Acid Bacteria From Kumiss And Study On Physicochemical Properties Of Bacteriocin

In this study, Sixty-seven strains of lactic acid bacteria were isolated from five samples of Koumiss collected from in Inner Mongolia In Xilinguole Meng region. With the Salmonella and Pseudomonas fluorescens as indicator bacteria,through the Oxford cup double agar diffusion method, after eliminating the interference of organic acids and hydrogen peroxidea.Screeneing 2 strains of bacteriocin producing lactic acid bacteria strains XME2 and XMD6 by the protease sensitivity test. The two strains of lactic acid bacteria were identified by traditional morphological, physiological and biochemical method and 16S rRNA gene sequence homology analysis, the strain XME2 is identified as L.plantarum and the strain XMD6 is identified as E.durans.Study on the physicochemical properties of two strains of lactic acid bacteria bacteriocin production:two bacteriocins are sensitive to protease,4℃, UV, methanol, ethanol, acetone, butanol, Na+, Fe2+, Ca2+, Ba2+, Tween-20, Tween-80 and SDS have no significant effect on the antibacterial activity of bacteriocin.-20 ℃, trichloroethane and Triton X-100 can reduce the antimicrobial activity of bacteriocin. Mg2+ and Zn2+ can slightly enhance the antimicrobial activity of bacteriocin and EDTA can significantly enhance the antimicrobial activity of bacteriocin. The bacteriocin of strain XME2 temperature stability,121 ℃ can still maintain above 90% activity, in the pH range of 2-6 have antibacterial activity. The bacteriocin of strain XMD6 heat-stable at 80 ℃, pH 2-7 has antibacterial effects.The antibacterial mode of bacteriocin for the indicator bacteria are sterilization, reduce the living indicator bacteria number 2-3 orders of magnitude.and can inhibit the gram positive and gram negative pathogenic bacteria and spoilage bacteria in food, has a wider antibacterial spectrum.