The Preliminary Study Of Bacteriocin Produced By Lactobacillus Plantarum And It's Apply On Pickled Vegetable

A LAB strain, producing a novel broad-spectrum bacteriocin, was screened from the traditional fermented food in Sichuan province. By studying the strain fermentation conditions, biological property and it's apply on pickled vegetable in order to afford theoretic data for the exploiture and application of microbial bio-preservative in food industry.1. 267 LAB strains were isolated from Sichuan traditional fermented food. Using agar plate proliferation, 64 LAB strains which can inhibit indicator strains (Escherichia coli ATCC25922, Staphylococcus aureus ATCC25923, Micrococcus luteus 10209, Pseudomonas aeruginosa ATCC27853 and Bacillus subtilis) were screened from those isolated LABs. The LAB P158 strain could inhibit indicator strains (Micrococcus luteus 10209 and Pseudomonas aeruginosa ATCC27853) strongly excluding the disturbances of organic acid and H₂O₂ by using double-layer agar plate proliferation, but the inhibition decreased sharply after the treatment with trypsin and pepsin. The results confirmed that this inhibitory material was a kind of protein and it could inhibit both G⁺ and G^-strains, so it could be classed as a broad-spectrun bacteriocin. According to morphological, physiological properties and 16S rDNA sequence (Accession No. EF114393) analysis, P158 strain was identified as Lactobacillus plantarum.2. Optimized the condition of bacteriocin production, research was done on five types of medias, the incubation condition and the media components. The optimum incubation time was 42h without shaking, the optimum temperature was 34℃, the optimum broth initial pH was 6.0. The optimum inoculating amount was 3%. And the optimum media's component was: glucose 2%, soybean peptone 1.5%, yeast extract 2%, K₂HPO₄ 0.2%, NaAc 0.5%, MGSO40.58%, MnSO4 0.25%,FESO40.04%, Tween 80 0.08%. With the fermentation condition, the relative active of P158 was 1145IU/mL, raise 216%.3. The biological property of bacteriocin of L. plantarum P158 indicated that P158 cultured best on 36h, but have the best active against Micrococcus luteus and Pseudomonas aeruginosa on 40h, and have the lowest pH at the same time. The bacteriocin of P158 was steady in acid conditions and it had good thermal stability. It was sensitive to proteinase. It was sensitive to antibiotics. It had broad antimicrobial spectrum, was active against G^-strains(such as E. coli), G⁺ strains(such as Micrococeus luteus) and could inhibit some fungi, but almost have no active against LABs. The experiment of plasrnid elimination confirmed that the gene was not located on the plasmid.4. The technology parameters to produce the semisolid pickled vegetables inoculated P158 were researched and optimized, and the quality of the products were improved. The traditional submerged pickled vegetables which were inoculated P158 and the traditional natural fermented pickled vegetables were compared with the semisolid one and the organoleptic, the chemical and the microbiological quality were studied. The results indicated that there were few discrepancies between the inoculated submerged and the inoculated semisolid one, but they both were evidently better than the traditional natural fermented pickled vegetables.