Study On The Bacteriocin-producing Enterococcus Isolated From Traditional Cheeses In And Probiotic Properties From Cheeses In Northern Regions In Xinjiang

Enterococcus are widely distributed in nature. It’s normal bacteria in human body. Enterococcus often colonize in the digestive system in human and animals. Enterococcus are not only common pathogens of nosocomial infection, but also as an important microbial flora in some foods. Enterococcus could product organic acid, diacetyl, hydrogen peroxide, bacteriocin and other bacteriostasis component. These substances could inhibit the growth of some foodborne pathogenic bacteria and the spoilage organisms. bacteriocins produced by Enterococcus represent a potentially safe class of biopreservatives for use in the food industry because of their sensitivity to proteolytic enzymes.The objebtives of this study were isolated LAB in different regions of the northern XinJiang traditional cheeses and researched the diverdity of Enterococcus. Bacteriocin-producing Enterococcus strains were screened and characterizated by agar well diffusion method. Bacteriocin stability was studied in different temperature, pH, surfactants and enzymes. Combined the molecular technology to analyze the genetic difference of Enterococcus. Screening the high yeild of bacteriocin- producing Enterococcus strains and studying these strains probiotic properties will as a food additive, pharmaceutical preparations, animal feed applied in practicial production.653 strains of E. Faecalis 、E. Faecium、E.durans and E.hirae, using three primers Box-PCR molecular genetics technical study the strains which the 16 S r RNA gene secquences have high similarity. 168 represented strains were used to inhibition experiment. 17 strains showed antimicrobial activity after eliminating organic acid and hydrogen peroxide. The activity of all tested strains was lost after treatment with proteinases and the inhibitory compound was proteinaceous in nature.Three strains named B92-YMX1-EL-2 、 BT3-TLX-CQ-8 and B78-TLX-M17-4 showing obvious inhibitory activities against Listeria monocytogenes were selected for further characterization. The results suggested that the inhibitory substances from the three strains were stable to heat(60°C-100°C) and to treatment with surfactants, active over a quite wide pH range(2-10), and the antimicrobial activity was lost after treatment with proteinase K, trypsin and pepsin. Bacteriocin-producing LAB was found to have a potential application as a biopreservative in food industry.Studying the probiotic properties form bacteriocin-producing Enterococcus.In order to study the possibility of development and research the probiotic properties,these 17 tested strains were operated by physiological and biochemical characteristics、sugar fermentation experiments、V- P and bile salt resistance experiment.