Nature 557, 434–438 (2018)

The human gut microbiome plays a key role in maintaining the health of its host, with certain compositions being implicated in diseases such as diabetes and autism. The composition of the gut microbiome is stable over time, which can prevent newly introduced bacterial strains from successfully colonizing. To better understand how new bacterial strains can be stably and predictably integrated into a pre-existing microbiota, Shepherd et al. performed experiments where they introduced a rare strain of the commensal species Bacteroides ovatus, NB001, into mice colonized with different complex microbiotas, some of which were donated from humans. NB001 is able to utilize the polysaccharide porphyran, which is abundant in seaweed, so that when NB001 was introduced into any of the mice, even those with the most resistant microbiota, there was a predictable increase in the levels of NB001 if the mice were fed seaweed. This effect was dependent on the NB001 genes required for porphyran metabolism and was observed in the specialized microhabitat of the colonic crypts. NB001 abundance upon engraftment could be tuned by varying the amount of porphyran fed to the mice. These results highlight the powerful influence of nutrient availability in shaping microbiota membership and have implications for treating disease by manipulating microbiota composition.

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Nature