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Asia differs substantially among and within its regions populated by diverse ethnic groups, which maintain their own respective cultures and dietary habits. To address the diversity in their gut microbiota, we characterized the bacterial community in fecal samples obtained from 303 school-age children living in urban or rural regions in five countries spanning temperate and tropical areas of Asia. The microbiota profiled for the 303 subjects were classified into two enterotype-like clusters, each driven by Prevotella (P-type) or Bifidobacterium/Bacteroides (BB-type), respectively. Majority in China, Japan and Taiwan harbored BB-type, whereas those from Indonesia and Khon Kaen in Thailand mainly harbored P-type. The P-type microbiota was characterized by a more conserved bacterial community sharing a greater number of type-specific phylotypes. Predictive metagenomics suggests higher and lower activity of carbohydrate digestion and bile acid biosynthesis, respectively, in P-type subjects, reflecting their high intake of diets rich in resistant starch. Random-forest analysis classified their fecal species community as mirroring location of resident country, suggesting eco-geographical factors shaping gut microbiota. In particular, children living in Japan harbored a less diversified microbiota with high abundance of Bifidobacterium and less number of potentially pathogenic bacteria, which may reflect their living environment and unique diet.

In this study, we isolated two lactobacillus strains, i.e., strain LAP5 and LF33, from swine and poultry, respectively, and showed that both strains were acid as well as bile tolerant and were able to adhere to the cultured human intestinal cell lines, such as Int-407 and Caco-2 cells, and to the intestinal epithelium cells isolated from swine, poultry and mouse (BALB/c). Both of these LAB strains were shown to inhibit the growth of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Bacillus cereus. When these two LAB strains were evaluated for their antagonistic activity against Salmonella (S. typhimurium) invasion to cultured human intestinal cell line Int-407 and to mouse (BALB/c) liver and spleen, these two LAB strains were found to have significant antagonistic effect.