The Investigation On Physiology Functional Characteristics Of Lactic Acid Bacterica And Its Applications

Lactic acid bacteria were important inhabitant in intestinal tracts of people and animals, which was widely distributed in nature, which had beneficial effects on intestinal health for their varieties and quantities. The research found that Lactic acid bacteria had a lot of helpful effects, such as adjustment intestinal metabolize, and improvement internal environment pH value. There were many kinds of Lactic acid bacteria, but different kinds of bacteria's functional mechanisms were not clear. Identification and physiological function of Lactic acid bacteria and its application were investigated systematically by five experiments in vitro and in vivo. They were included isolation and identification of Lactic acid bacteria, comparision of growth characteristic in different enviroments, antibacterial ability of Lactic acid bacteria to harmful organisms, cholesterol-degrading testing in vitro and in vivo. By these experiments, the isolated Lactic acid bacteria were systematically studied on identification, physiological function and cholesterol-degrading function.20 strains lactic acid bacteria were isolated and identified from natural fermented vegetable and acidophilus milk in MRS medium. Acid production quantity of each strain were determined, 6 strains with stronger acid producing ability were screened and identified, which were Lactobacillus plantarum, Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus brevis, respectively.Growth, acidic ability and salinity of six strains were compared in MRS medium. The result showed that all of those strains have slow growth, and the growth cycles are long. The strain S2 grew faster than other strains while the other strains grew slower and the lay phases were longer. The results of acidic ability and salinity indicated that the most suitable pH of the lactic acid bacteria were 6-7. Other else, with more salt in medium, a few of lactic acid bacteria could live. According to identified and antibacterial experiment, it is found that 6 strains had stronger antibacterial ability to Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, but little antibacterial ability to Bacillus aeruginosum and Canidia Albicans. Besides, it was correlative between stronger acid producing ability with antibacterial ability. The study provides an evidence for the Lactic acid bacteria using in the food antisepsis.Cholesterol-degrading function of the Lactic acid bacteria isolated from natural fermented vegetable and acidophilus milk in vitro and in vivo proved that the both strains have cholesterol-degrading function. Meanwhile, the mixed fermentation strains had the best effect.It could be concluded from the above results that lactic acid bacteria which separated from natural fermented vegetable and acidophilus milk had good antibacterial ability and cholesterol-degrading function, had tremendous development and application potentials.