B. subtilis is a soil dwelling bacterium with a diverse social life that includes quorum sensing-regulated interactions 1. These interactions result in bacterial equivalent of sex, and subsequently have a profound influence on bacterial evolution2. Sexual isolation in B. subtilis predicts for more frequent uptake of DNA isolated from closely related strains3–5, but DNA exchange between two interacting B. subtilis strains has never been addressed previously. Recently we discovered kin discrimination among highly related strains of B. subtilis, where less related strains showed antagonistic behaviour towards each other in the form of killing6. Here we show that antagonistic interactions between two less closely related B. subtilis strains result in increased recombination, which is in contrast to current dogma. We demonstrate that the induction of competence between non-kin strains is responsible for the observed elevated DNA uptake, which, through increased genetic variation, can increase the rate of adaptation as demonstrated here by the successful exploitation of a novel adaptive zone by a recombinant strain. Our results demonstrate an important evolutionary mechanism of ‘’promiscuous but safe sex’’: a type of bacterial cell-contact dependent DNA exchange that could promote diversification of conspecifics and exclude non-specific and potentially risky DNA of other species. Our findings could help understand the vast diversity of B. subtilis species at the genomic level despite existing mechanisms limiting less-related DNA integration during transformation. It is possible that this (or similar) mechanism could be accountable for the diversification of many other bacterial species capable of natural transformation.
Spatiotemporal Analysis of DNA Integration during Natural Transformation Reveals a Mode of Nongenetic Inheritance in Bacteria
