Quorum sensing increases survival species and alters community diversity in a Lotka-Volterra model

Quorum Sensing (QS) is a type of signaling in bacteria communities in which gene expression changes after the cell density reaches a certain value. Experiments have shown that QS plays a role in shaping the diversity and composition of microbial communities in the wild, but it remains unclear what impact QS will generally have on the composition of bacterial communities.

To answer this question, we used a generalized Lotka-Volterra model to investigate the microbial community dynamics. Lotka-Volterra models have been widely used to infer how community composition is impacted by species-species interactions, however QS has not yet been incorporated into such modeling efforts. Community dynamics were simulated with random Lotka-Volterra interactions. In some communities, a few of the species were capable of QS, which is captured by a cell density-dependent change in these interaction coefficients. The impact of QS was quantified using the number of survival strains and the Shannon biodiversity index as measurements of the community composition. A statistical analysis of data showed that on average QS increased the number of survival strains, although biodiversity was slightly affected. A QS species was more likely to survive when QS is activated. These results were confirmed over a broad range of parameters including population size, coefficients distribution variance, carrying capacity, and the dependency of interaction coefficients with cell density.