(251b) Spatiotemporal Modulation of Biodiversity in a Synthetic Predator-Prey Ecosystem

Biodiversity is a central element in determining the structure and functionality of natural ecological systems. Its maintenance and modulation is poorly understood due to difficulties in studying this phenomenon with natural ecosystems. To this end, we have used a synthetic predator-prey ecosystem to examine effects of cellular motility and spatial configuration on biodiversity. This synthetic ecosystem consists of two Escherichia coli populations, which communicate bi-directionally through quorum sensing signaling and regulate each other's gene expression and survival via engineered gene circuits. We found that cellular motility had a negligible impact on the biodiversity when the predator and prey cells were well-mixed in either liquid phase or soft agar. Increasing inoculation distance between the two populations on soft agar, however, caused increased biodiversity. The seemingly different roles of spatial segregation and cellular motility on biodiversity can be attributed to the existence of a critical segregation distance between the predator and prey cells, as revealed by a mathematical model that accounts for the spatiotemporal dynamics of the system. Below the critical distance, cellular motility has a negligible effect; beyond it, however, biodiversity scales almost linearly with cellular motility. Our results reveal the critical importance of the interplay between cellular motility, spatial segregation, and communication for the maintenance of biodiversity in chemical-mediated ecosystems.