From a bacterium's point of view, the human gut is not the best place to set up home, with low pH and little oxygen or light. Thus, bacteria have had to evolve means of surviving in this challenging environment, which this study now begins to unveil. The scientists identified the genes that each individual bacterium needs to survive in the human gut, as well as those that have to be present for the community to thrive, but not necessarily in all individuals, since if one species produces a necessary compound, others may not have to. This could explain another of the scientists' findings, namely that the gut microbiomes of individual humans are more similar than previously thought: there appears to be a common set of genes which are present in different humans, probably because they ensure that crucial functions are carried out. In the future, the scientists would like to investigate whether the same or different species of bacteria contribute those genes in different humans.

The research was conducted within the European project MetaHIT, coordinated by Dusko Ehrlich at the Institut National de la Recherche Agronomique, in France, with genetic sequencing carried out by Jun Wang's team at the Beijing Genomics Institute at Shenzhen, China.

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