Abstract Multispecies microbial communities drive most ecosystems on Earth. Chemical and biological interactions within these communities can affect survival of individual members and the entire community. However, the prohibitively high number of possible interactions within a microbial community has made the characterization of factors that influence community development challenging. Here we report a Microbial Community Interaction (μCI) device to advance the systematic study of chemical and biological interactions within a microbial community. The μCI creates a combinatorial landscape made up of an array of triangular wells interconnected with circular wells, which each contains either a different chemical or microbial strain, generating chemical gradients and revealing biological interactions. Bacillus cereus UW85 containing GFP provided the “target” readout in the triangular wells, and antibiotics or microorganisms in adjacent circular wells are designated the “variables”. The μCI device revealed that gentamicin and vancomycin are antagonistic to each other in inhibiting the target B. cereus UW85, displaying weaker inhibitory activity when used in combination than alone. We identified three-member communities constructed with isolates from the plant rhizosphere that increased or decreased growth of B. cereus . The μCI device enables both strain-level and community-level insight. The scalable geometric design of the μCI device enables experiments with high combinatorial efficiency, thereby providing a simple, scalable platform for systematic interrogation of three-factor interactions that influence microorganisms in solitary or community life.

Microbial Community Interactions on a Chip