Lactobacillus spp., referred to as IJ-1 and IJ-2, were isolated from the feces of breast-feeding piglets and analyzed for probiotic properties. According to the analyses of 16S rDNA sequence, Lactobacillus sp. IJ-1 showed greater than 99% homology with Lactobacillus reuteri DSM 20016(T), and Lactobacillus sp. IJ-2 had greater than 99% homology with the L gasser! ATCC 33323 and L. johnsonii ATCC 33200(T). The pH changes in the culture media of Lactobacillus sp. IJ-1 and Lactobacillus sp. IJ-2 were from 6.5 to 4.2 and 4.6, respectively. Their respective resistance against artificial gastric acid and artificial bile acid led to survival rates of nearly 186 +/- 44% and 13 +/- 5%. Neither strain produced the carcinogenic enzyme beta-glucuronidase. Both strains inhibited the growth of pathogenic microorganisms, such as Listeria monocytogenes ATCC 19111, Salmonella enterica KCTC 12401, Salmonella enteritidis ATCC 13076, Staphylococcus aureus KCTC 3881, and Bacillus cereus 3711, within 24 h of growth. (C) 2009, The Society for Biotechnology, Japan. All rights reserved.