Isolation And Identification Of Bacteriocin-producing Lactic Acid And Cloning Genes Associated With Resistance To Acid

Lactobacillus is a kind of probiotics, which is widely used in food fermentationindustry. Its metabolic product——lactobacillin has effects on anti-bacteria, it isrecognized as the safe, efficient and reliable food preservative. In recent years, peoplebegin to look for natural and security preservative as substitute because foodpathogenic bacteria and synthetic preservatives are aggravating hazard. People paymore attention to the lactobacillin due to good antibacterial activity and security, atthe same time, which is also thought to the most ideal alternative to antibioticsbecause it has incomparable advantages of efficient, non-toxic, no residue and noresistance.In this study, taking3sources of Lactobacillus from chengdu in sichuanprovince millet pickled peppers, hongyuan yak yogurt and yak intestinal mucosa asresearch object。The antibacterial activity of lactobacillus is picked out using MRSselected medium, and carrying on the preliminary research, the main contents are:(1)Five strains of enterococcus faecalis (B13, B17, B20, C5and C12),4strains oflactobacillus (G1, G2, G4and G5) and1strains of lactococcus (G3) are separated andidentified through the morphological observation, conventional physiological andbiochemical characteristics analysis and16S rRNA molecule identification.(2) Takinglactobacillin of10strains of bacterial strains as the research object, bacteriostatic testfinding that its lactobacillin can not only inhibit gram-positive bacteria (such asbacillus subtilis and staphylococcus aureus), but also inhibit gram-negative bacteria(such as escherichia coli, Shigella and salmonella); Lactobacillin has the higher titer，to a maximum of17.47×105IU/mL；It is Sensitive to trypsin and proteinase K and isnot sensitive to pepsin; heatstable and acid stability. After the single test，we got thebest inoculation amount4%, the optimum temperature34℃and pH6.(3)Cloning3genes (sppK, JSA and JSB) related to lactobacillin, the results show that the similaritybetween cloned sppK sequence and sppK sequence published on NCBI is100%; thesimilarity between cloned JSA sequence and JSA sequence published on NCBI is 91%；the similarity between cloned JSB sequence and JSB sequence published onNCBI is93%，the translated protein through reading frame1is hydrophobic protein,includingAlpha helix and Random coil.