Screening And Researching Of Lactobacillus To Produce Anti-listeria Bacteriocin

Listeria monocytogenes is a bacterium with strong adaptability and can cause seriousfoodborne disease, such as meningitis, sepsis and abortion. Bacteriocins from lactic acidbacteriocin is some small molecule peptide or protein substances with the bactericidal orbacteriostatic effect produced by lactic acid bacteriocin. Because of its efficient, non-toxic, noresidue, no drug resistance and other characteristics, it has become a research focus of foodpreservative, and is considered to be the most promising natural products instead of antibiotics.Using L. monocytogenes as indicator bacteria, the strain ZLG85with the antagonistic toindicator bacteria was screened from200strains isolated from the traditional fermented picklesafter excluding the influence of H2O2and organic acids by double agar diffusion. The nature ofinhibitory substance of strain ZLG85was determined as bacteriocin by the degradationexperiments of pepsin, trypsin, and neutral protease. By appearance detection, physiologicaland biochemical characteristics analysis and16S rDNA gene sequence homology analysis, thestrain ZLG85was identified as Leuconstoc mesenteroides subsp mesenteroides.The mesentericin ZLG85was extracted and purified, and the molecular weight wasdetermined. Using80%(V/V) cold ethanol precipitation, the mesentericin ZLG85waspreliminarily extracted. Using Sephadex G-25gel, the mesentericin ZLG85was carried outfiltration chromatography at sample volume3mL and elution rate0.8mL/min. After purified,the purification time was25.37, the activity of bacteriocin was60185AU/mL. The molecularweight of mesentericin ZLG85was2.5kDa conformed by Tricine-SDS-PAGE electrophoresis.The study of mesentericin ZLG85’s antibacterial spectrum shows that it could inhibit thegrowth of Listeria monocytogenes, Staphylococcus aureus, Micrococcus luteus, Bacillus subtilis,Salmonella paratyphi, Shigella dysentery et al. The experimental results showed thatmesentericin ZLG85had thermal and pH stability, was highly sensitive to papain, pepsin,protease, neutral protease and trypsin. K+, Na+, Mg2+, Ca2+, Zn2+had significant effect on theantibacterial activity of mesentericin ZLG85(P<0.05), and organic solvents didn’t havesignificant effect on the antibacterial activity (P>0.05).Both molecular weight and antibacterial spectrum of mesentericin ZLG85were differencefrom the known mesentericin, and it is a new type of broad-spectrum mesentericin.