Antibacterical Effect Of Lactobacillus And Its Application

It has a long history of Lactic acid bacteria fermented food, and which could not only improve the flavors and the nutritional values of food, but also have special nutritional values and physiological activities. A large number of studies have showed that lactic acid bacteria can regulate the body normal flora of the gastrointestinal tract, thus inhibiting the growth of intestinal pathogen. Its metabolites which produced by fermentation products also have inhibition of fungal growth and other effects. Because of high efficiency, non-toxic, no residue, no drug resistance and other advantages, they could be added to improve the qualities of meat and the rate of feed conversion.Basic characteristic revealed that the strain had homology to Lactobacillus plantarum. So we named this strain as Lactobacillus plantarum ZJ316 and the bacteriocin as plantaricin ZJ316. In this paper, preliminary studies were done including the purification of bacteriocin ZJ316, its propercities of anti-bacterial and the experiments of feeding piglets.In the anti-fungal experiments, with the determination of double-plate antagonism method, the results showed that Lactobacillus plantarum ZJ316 had anti-fungal activities.Purification of bacteriocin ZJ316. First, aqueous two-phase extraction using a preliminary separation, the best extraction conditions of PEG/ammonium sulfate system were 17.5% PEG4000,19% ammonium sulfate,1% sodium chloride and pH 3.75. Under these conditions the titer was:287.56 IU/mL. The best extraction conditions of PEG/sodium sulfate were 17% PEG 1000,15% sodium sulfate,1% sodium chloride, pH 3.5, the titer was:256 IU/mLThe ion column was selected for purification. The results showed that a more pure-component bacteriocin could be reached by selecting pH 5.0 sodium acetate buffer, DEAE Sepharose FF. After using Trcine-SDS-PAGE electrophoresis, the results showed that the molecular weight of plantaricin ZJ316 was about 6.5 kDa, which was a small molecule peptide substances.In piglets feed tests, it was explored that Lactobacillus plantarum ZJ316 as an feed additive. The results showed that, with the addition of Lactobacillus plantarum ZJ316, the daily gains and the rate of feed conversion had been improved; the rates of diarrhea and mortality were reduced, it had the same anti-fungal effects as mequindox; also it had certain improvements in qualities of meat. With the paraffin sections of small intestine of piglets and observing the morphological changes of small intestine of piglets, it was found that Lactobacillus plantarum ZJ316 had significant effects on small intestine of piglets, which supported the results that the daily gains, the rate of feed conversion and the qualities of meat of experimental group were better than control group from physiological points.