Prokaryotes can exchange DNA without sharing a parent-offspring relationship, a process called horizontal gene transfer (HGT). HGT can occur via natural transformation, i.e., via uptake and integration of extracellular DNA into the recipient cell’s chromosome, and naturally competent bacteria possess a conserved and diverse molecular machinery for that purpose. Several physicochemical factors affect natural competence, but it is unknown if and how macroecological factors, like community diversity, also affect it. This is a plausible hypothesis because the proteins mediating natural competence also mediate quorum sensing (QS) for some bacteria, suggesting that these bacteria might regulate their competence depending on the surrounding community. This hypothesis is, however, hard to examine in natural communities where diversity and natural competence are hard to manipulate and monitor, respectively. Here, we examined this hypothesis in 3,000 synthetic communities with increasing species richness (S) and phylogenetic diversity (PD) using a reporter strain to monitor natural competence and a replicated, randomized and blind experiment. We found that transformation rate increases with increasing S and PD, indicating that natural competence is favored in more diverse communities. Evolutionary, that gives an advantage to naturally competent bacteria, increasing their chances of acquiring novel traits in communities with increasing genetic repertoire.
Adriana Valenzuela Cuevas Ph.D. candidate in the bioscience program at KAUST in Daffonchio’s Lab. My project is focused on mechanisms of bacterial community assembly using synthetic ecology techniques to create simplified bacterial communities.