The Application And Preliminary Study On A Lactobacillus Plantarum Strain Producing A Bacteriocin

Lactic acid bacteria has become an important topic in research work, because of its probiotic function, and abundant natural resources of in China. Since 1928, the bacteriocin produced by lactic acid bacteria have been interested and payed more attention by many researchers, due to it's non-toxic, non-residual, non-drug-resistant. It is also considered to be the most effective antibiotic alternatives and synthetic preservatives.The chief aim of this paper is to purify the bacteriocin from Lactoba-cillus plantarum, and to increase its yield by optimizing the fermentation conditions, to assess the effects of weanling piglets by Lactobacillus plantarum as feed additive substituting antibiotics.There are three main parts in the article:1) Methods on the effects on puritification of the bacteriocin was obtained. Adsorption method, ammonium sulfate salting out method and Binary Aqueous Phase Extraction were tested. In the PEG/(NH4)2SO4 Two-Phase System, the best condition was 17.971% PEG 2000,18.430% ammonium sulfate,1% NaCl, and the pH was 3.766. Then, adopting gel chromatography (The mobile phase is water, the flow speed is 1 mL/min); then, it explored the kinds of Anion-exchange Chromatography methods of further purification study, optimum condition was DEAE Sepharose FF Chromatography, the flow speed was 1 mL/min, and equilibrium liquid was 20 mmol/L sodium acetate-acetate buffer solution (pH 5.4), and elution buffer consiste of 1 M sodium chloride in the equilibrium liquid; and the molecular size of plantaricin ZJ317 was about 4 kDa by Tricine-SDS-PAGE electrophoresis.2) By single factor experiments, PB experiments, steepest ascent exp-eriment and the central composite design, the optimal condition described as follows:2.15% glucoses,1.50% Maltoses,0.5% peptones,1.60% concent-rated yeast extracts,0.2% potassium dihydrogen phosphates,0.5% sodium acetates,0.2% lemon acid,3% rubber ammoniums,0.02% Magnesium sul-fate heptahydrate,0.005% manganese,0.2% Tween 80; the optimal inocu-lation number was 5%, and the optimal medium volume was 20 mL/50mL with erlenmeyer flask, optimal fermentation conditions of 37℃, the initial pH value of 6.5, compared with non-optimization, the activity of lactein enhance 60.2%.3) Application of the feed additive with plantaricin ZJ317and fermen-tation liquor, it investigated the effect of feeding weaning pigs, the study indicated that:adding plantaricin ZJ317 and fermentation liquor increase feed conversion efficiency and daily gain of the weaned piglets; diarrhea rate and mortality made no significant difference in performance in piglets, compared to the control. Investigation of meat quality showed that the color and pH of meat was normal range, the qualities of water holding capacity and meat tenderness have been improved. They are markedly inhibitory to some of bacterial pathogens from diarrhea rate and mortality aspects, such as antibiotics, using PCR-DGGE technology, therefore, they can replace the antibiotics as feed additives.