An American study has revealed that a combination of bacterial genes, rather than any particular bug species, is crucial to digestion and metabolism.
Jeffrey Gordon, who led the study at Washington University School of Medicine in St. Louis, Missouri, said that it is commonly believed that the "good" bacteria in the guts helps digest food, and that's why his team set out to find a core group of bacterial species that aid digestion.
He revealed that the team expected to find these species living in the guts of most healthy people. However, upon analysing faeces from 154 people, they found that it was not so.
The subjects did, however, all possess the same core group of bacterial genes needed for digestion, albeit from different species.
Gordon said that it's this combination of genes, rather than any particular species, that is necessary for a healthy gut.
"We've learned that you can have different collections of species, yet the gene functions represented in these collections are broadly shared," New Scientist quoted Gordon, as saying.
The study also flagged up differences between the bacterial genes of obese and lean people.
Obese individuals had a greater proportion of genes for digesting fat, protein and carbohydrates, which might make them better at extracting and storing energy from food.
Gordon hopes that a better knowledge of these genes might suggest new ways of combating obesity.
The study is published in the journal Nature.