Isolation Of Lactic Acid Bacteria From Swine And Research On Antagonism Function To Salmonella Infection By Oral Administration To Mice

Lactic acid bacteria (LAB) commonly found in human and animal is generally regardedas safety (GRAS) by international and is widely used in the field of probiotics, fermentedfoods and oral vaccine. Long-term use of antibiotics have effect on sterilization andantibacterial, but caused a lot of side effects, such as drug-resistant strains increased,resistance enhanced, diffusion of resistance factor, disorder of intestinal flora, damage ofbiological barrier, functional disorders and so on. People choose the safe, non-toxic sideeffects ways to improve production. LAB probiotics or oral vaccines can be fed animalsdirectly. Live bacteria in the digestive tract can adjust the microorganism balance of thegastrointestinal tract, inhibit the growth of pathogenic microorganisms, and improve theanimal immunity.The types of LAB were used variedly. It should be noted that there are specialrelationships between intestinal bacteria and the host. In order to give full play, the idealbacteria should come from the homologous animals. This study was to separate the excellencelactic acid bacteria from pig intestines and feces. Analysis was to determine its safety andprotective immunity by animal experiments, and to construct the LAB expression vectors. Soas to provide theoretical support and reliable bacteria for choosing a more suitable pig feedadditives and oral vaccines. The main research contents and results are as follows:1. Isolation and Characterization of Lactic Acid Bacteria from SwineTwenty seven strains of lactic acid bacteria were isolated from feces and intestinalmucosa of two Bamei species pigs, one origin of northwest Chinese local pig breeds, amongwhich, two excellent lactic acid bacteria strains were selected by the experiments of acid andbile resistance, cell adherence and antimicrobial activity. The one strain named FB027hasbetter cell adherence activity, and the other strain named SE013has better acid and bileresistance. Furthermore, the two weeks continuous oral administrations of FB027and SE013to mice confirmed that the two strains were healthy and without obviously abnormalbehaviors, slow growth, declining food intake and typical anatomo pathological change. Thus, the result proved that the two strains have part features of function probiotics, and express theexcellence biological safety in animals.2. Antagonistic function studies on Salmonella invasion to mice of lactic acid bacteriaFB027and SE013Immune protection features of lactic acid bacteria FB027and SE013in vivo wereanalysised through Salmonella infection experiments to mice. In vivo results indicated that,compere to PBS group, after Salmonella infection, mice administered LAB SE013and FB027could reduce the MDA levers in liver and Nitrite levels in serum, increase GSH levelobviously in mice liver, cut down the salmonella number in liver and spleen and remithepatomegaly and weight loss. So, the two strains had antagonistic effect to salmonellainfection. Therefore, we preliminary concluded that the lactic acid bacteria FB027and SE013can be used as probiotics feed additives for pigs.