Isolation and characterization of potential probiotic lactobacilli from pig feces

This study examined four lactobacilli isolated from pig feces. Two hundred lactic acid bacteria strains were obtained from pig feces using selective culture media (with vancomycin and bromocresol green; termed LAMVAB agar). Microscopy, the catalase test, Gram-staining, and RAPD-PCR analysis were used to group the bacteria into 20 related clusters. Phenotypic analysis using the API 50 CH test and genotypic analysis of 16S rDNA sequences identified these clusters as representing single strains of each of Lactobacillus fermentum, Lactobacillus salivarius, Lactobacillus plantarum, and Lactobacillus reuteri. Bacterial survival under the conditions of low pH (2.0) and high concentration (5.0%, w/v) of bile salt was much better than that of the reference strain (Lactobacillus acidophilus ATCC 33199). The isolated bacteria were quite capable of inhibiting the growth of two pathogens, Escherichia coli K88 and Salmonella typhimurium. The high acid-resistance, bile resistance and antagonism against pathogens, suggest that the four lactic acid bacteria isolated from pig feces could prove useful as piglet probiotics.