Abstract: Ten strains of lactic acid bacteria (LAB) were isolated from the digestive tract of pigs by anaerobic culture. Based on morphological, physiological, biochemical tests and 16S rDNA sequence analysis, five strains were identified as Lactobacillus plantarum, four strains as Enterococcus faecalis, and stain m661 as Enterococcus gallinarum. All ten strains had strong radical-scavenging capacity although E. faecalis M462 and L. plantarum M15 had almost no scavenging capacity against hydroxyl free radicals. The radical-scavenging capacity of most of the ten strains was positively correlated with bacterial density. At a concentration of 5 × 108 CFU/mL, the highest radical-scavenging rates against hydroxyl, superoxide anion and DPPH free radicals were 12.2%, 80.6% and 79.3%, respectively. Five L. plantarum strains revealed a DPPH scavenging rate of higher than 60%, which was significantly higher that that of four Enterococcus faecalis strains. E. faecalis had better scavenging effect against superoxide anion free radicals than other two species and the scavenging rates of four E. faecalis strains against superoxide anion free radicals were all higher than 60%. L. plantarum strains R17, R53 and R762 revealed a scavenging rate of higher than 5% against superoxide anion free radicals, and R17 was the strongest superoxide anion free radical scavenger among them.

Key words: pig, lactic acid bacteria, identification, antioxidant effect