In Vitro Communities Derived from Oral and Gut Microbial Floras Inhibit the Growth of Bacteria of Foreign Origins |
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Authors: | Xuesong He Yan Tian Lihong Guo Takashi Ano Renate Lux David R Zusman Wenyuan Shi |
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Institution: | (1) UCLA School of Dentistry, 10833 Le Conte Avenue, CHS 20-114, Los Angeles, CA 90095-1668, USA;(2) Department of Oral Biology, Peking University School and Hospital of Stomatology, 22 Zhong Guan Cun Nan Da Jie, Haidian District, Beijing, 100081, China;(3) Department of Biotechnological Science, Kinki University, Kinokawa City Wakayama, 649-6493, Japan;(4) Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; |
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Abstract: | The gastrointestinal (GI) tract is home to trillions of microbes. Within the same GI tract, substantial differences in the
bacterial species that inhabit the oral cavity and intestinal tract have been noted. While the influence of host environments
and nutritional availability in shaping different microbial communities is widely accepted, we hypothesize that the existing
microbial flora also plays a role in selecting the bacterial species that are being integrated into the community. In this
study, we used cultivable microbial communities isolated from different parts of the GI tract of mice (oral cavity and intestines)
as a model system to examine this hypothesis. Microbes from these two areas were harvested and cultured using the same nutritional
conditions, which led to two distinct microbial communities, each with about 20 different species as revealed by PCR-based
denaturing gradient gel electrophoresis analysis. In vitro community competition assays showed that the two microbial floras
exhibited antagonistic interactions toward each other. More interestingly, all the original isolates tested and their closely
related species displayed striking community preferences: They persisted when introduced into the bacterial community of the
same origin, while their viable count declined more than three orders of magnitude after 4 days of coincubation with the microbial
flora of foreign origin. These results suggest that an existing microbial community might impose a selective pressure on incoming
foreign bacterial species independent of host selection. The observed inter-flora interactions could contribute to the protective
effect of established microbial communities against the integration of foreign bacteria to maintain the stability of the existing
communities. |
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