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The evolution of cooperation within the gut microbiota
Seth Rakoff-Nahoum1,2, Kevin R Foster3, Laurie E Comstock2
1Division of Infectious Diseases, Department of Medicine, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts 02115, USA.
Nature
|April 26, 2016
Summary
Cooperation is vital in the human gut microbiome. Researchers found that Bacteroides ovatus exhibits evolved cooperation by digesting inulin, benefiting other gut microbes and increasing its own fitness.
Area of Science:
- Microbiology
- Ecology
- Evolutionary Biology
Background:
- Microbial communities are essential for human health.
- Cooperative behaviors, like quorum sensing and biofilm formation, are key to microbial community function.
- The extent of cooperation within the human intestinal ecosystem remains largely unknown.
Purpose of the Study:
- To investigate evolved cooperation in the human gut's dominant bacteria, Bacteroidales.
- To determine if Bacteroides thetaiotaomicron exhibits cooperation when utilizing dietary polysaccharides.
- To identify and characterize cooperative mechanisms in other prominent gut symbionts, such as Bacteroides ovatus.
Main Methods:
- Experimental evolution assays using Bacteroides thetaiotaomicron and its mutants.
- In vitro co-culture systems to study interactions between gut bacteria.
- Gnotobiotic mouse models to assess bacterial fitness and colonization in vivo.
- Enzyme assays to characterize polysaccharide digestion and cross-feeding.
Main Results:
- Bacteroides thetaiotaomicron showed limited cooperation when growing on certain dietary polysaccharides; mutants lacking extracellular digestion were outcompeted.
- Bacteroides ovatus possesses a specialized enzyme system for extracellular inulin digestion, incurring a cost but benefiting other species.
- This cross-feeding interaction in B. ovatus provides reciprocal benefits, enhancing its fitness when feeding species like Bacteroides vulgatus.
Conclusions:
- Naturally-evolved cooperation between microbial species is rare but significant in the mammalian gut.
- The study highlights the complexity of cooperative phenotypes in the human intestinal microbiota.
- Understanding microbial cooperation is crucial for comprehending gut ecosystem function and health.
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