There is little doubt that the microbial flora of the digestive system contributes to health and disease, but a detailed understanding of the role of particular microorganisms remains unclear. This is mainly due to the inaccessibility of the majority of the microbiome as most organisms of the intestinal flora remain uncultured. Metagenomic studies provide important information about the microbiome but in order to understand the role of individual microorganisms we have to be able to culture them. The goal of this study is to provide effective tools for the cultivation of such uncultured microorganisms. We recently developed a co-culture method that has been successfully used to culture previously uncultured microorganisms from marine sediment. These species could be grown on nutrient medium in the presence of other organisms from the same environment, but they did not grow without this help. We examined the co-culture approach for gut microorganisms. Serial dilutions of a feces sample were plated on BHI agar plates supplemented with yeast extract, cysteine and hemin. An Escherichia coli BW25113 culture was then spotted as a helper onto the plate. Following incubation, colonies growing in close proximity to the helper spot were collected and diluted suspensions were spread-plated on plates with and without a helper spot. Using this method we found that previously uncultured bacteria can be isolated from human feces in the presence of an appropriate cultivable helper organism, such as E. coli. We were able to isolate three strains that are dependent on E. coli BW25113, but do not grow on the same complex growth medium without help. The described method of co-culture will help us to isolate more uncultured microorganisms.
Full conference title:
110th General Meeting American Society for Microbiology
- ASM 110th (2010)