Purification Of Bacteriocin Produced By Lactic Acid Bacteria In Koumiss Of Xinjing Autonomous Region

With the increasing awareness on health and food safety, people more and more want todevelop safe and efficient biological preservatives instead of chemical preservatives whichexist health hazards. Bacteriocins from Lactic acid bacteria become the most studiedbacteriocins because of the huge development potential. Bacteriocins are a class of proteins orpeptides, secreted by bacteria, which can inhibit the growth of relative bacteria. One strain oflactic acid bacteria (LAB) which isolated from traditional Xinjiang fermented dairyproduct-koumiss had good inhibitory effect on S. aureus and E. coli. Then the antibacterialsubstance was purified and its physico-chemical properties were further studied. All thesework together established the base for new preservative. The main findings are as follows:(1)17strains of LAB were isolated from Koumiss. After the antibacterial test screening,4strains of LAB have antibacterial activity. One of the highest antibacterial activity of LABstrains named MN047was the object of this study, by16S rDNA phylogenetic analysis,identified as Lactobacillus crustorum.(2) First, crude extract obtained by ammonium sulfate precipitation, after HiTrap Q XLanion exchange column purified, and then purified by HPLC peak activity. Finally, with apurity of99.56%pure bacteriocins, Tris-Tricine electrophoresis revealed that the bacteriocinmolecular weight of about70kDa.(3) Physico-chemical stability of the bacteriocin from L. crustorum MN047. Inhibitoryactivity of bacteriocin had been maintained mostly after121℃for30min. In4℃for3months the activity of bacteriocin almost had no loss. The inhibitory proteins withstoodexposure to pH values between2and11. Bacteriocin activity was completely abolished byprotease treatment (pepsin, papain, trypsin and proteinase K). The bacteriocin has a wideantibacterial spectrum, both against Gram-positive bacteria also Gram-positive bacteria.