Quorum sensing promotes the emergence of antifragile regimes that increase bacterial communities' diversity

Understanding the mechanisms that shape bacterial community composition has implications in the ecology and evolution of both natural and synthetic microbial communities. Quorum sensing (QS), the regulation of cellular activity through signal exchange as a response to cell density, is a common mechanism of gene regulation in bacteria. The potential implications of QS in microbial community dynamics remain poorly understood. To investigate the impact of QS on community dynamics, QS-based changes in cellular activity were incorporated into a Lotka-Volterra (LV) model. Simulations approximated the dynamics of a multispecies bacterial community undergoing serial dilutions. The effects of QS were incorporated as an instantaneous and random change on interspecies interactions upon exceeding a threshold cell density. The addition of QS to the standard LV model increased the percentage of surviving species within the community, often benefiting both QS and non-QS species. This community benefit remained, even if incorporating reasonable energetic costs of QS. Competitive effects from QS cheater strains were tested: A noncheater strain was always outcompeted by cheaters when growing in a single population, while in a community context, the change of interspecies interactions due to QS increased the survival likelihood of the noncheater strain. Antifragile regimes, where variability enhances diversity, were promoted by QS, QS increased the variability of interactions, and higher variability increased community diversity. Our model generalizes prior ecological LV models with density-dependent interactions and shows that antifragile regimes induced from responses to a community's states (for example, through QS) might be an important mechanism to stabilize complex communities.