An article “Interspecies interactions drive bacterial proteome reorganization and emergent metabolism”, recently published by the Patil Group with colleagues in Berlin in Nature Ecology & Evolution, describes how culturing bacteria together profoundly changes how each species behaves.
They cultured human gut bacteria species in pairs on a large scale and measured proteins and metabolites to find out how each bacteria responded. Dr Stephan Kamrad, lead researcher on the study said, “We found a range of interaction types, with some bacteria competing with each other, others exploiting their neighbour, and some working together for mutual benefit”.
They found that factors including the overall number of different proteins that a species had, relative abundance of bacteria species, bacteria culture pH, and how similar the species were all influenced how many proteins changed in response to co-culturing.
In many cases the interactions between two species were complex, involving the exchange of multiple metabolites. That meant that the nature of the relationship changed if nutrients became scarce and some of the metabolites could not be produced.
They also identified the activation of genes with unknown function, including in relatively well studied bacterial species. Professor Kiran Patil, senior author said, “We identified the activation of genetic ‘dark matter’, genes that we don’t know the function of, by the presence of other species. This illustrates the potential of co-cultures to identify new functions for bacteria that only emerge in certain environments.”