Isolation of Lactobacillus Acidophilus with A High Acid-Producing Capacity and Its Common Characteristics

Abstract

Some strains of lactobacilli like spore Lactobacillus offer good merits in normalizing intestinal micro biota, resisting selectively to intestinal pathogens, exerting resistance to heat, acid and antibiotics, and are of good storage stability. This research work has been conducted in order to isolate a certain strain of Lactobacillus that offers high resistance to the gastric acid, bile and pathogens, and mutualistic symbiosis with useful intestinal microbes, and identifying its characteristics of actions. A strain of lactobaillus isolated from several sources was investigated in terms of its ability of lactic acid production and identified by examining the survival rate in self-made gastric juice and bile, and the ability of resisting to antibiotics, and symbiosis with useful intestinal microbes. Lactobacillus Acidophilus, isolated and identified, offers good resistance to self-made gastric juice and self-made bile, good antibacterial properties against pathogens, and good symbiosis with useful intestinal microbes. In the mixed culture of the isolated L. Acidophilus and Bifidobacterium bifidum, the number of these two species of bacteria increased significantly after 24 h rather than the single culture. The size of the inhibitory zone of the lactobacilli for E. coli, Shigelladysenteriae and paratyphoid bacillus was 15.3, 16.8, and 16.2 mm respectively. The survival rate of the isolated strain was 93.4% in the self-made gastric juice after 3 h whereas it was 88.0% in the 2% bile. It has good prospects of being widely used in prevention and treatment of intestinal infections.