Slavic, LaurenXiong, XianyiHarcombe, William2023-09-062023-09-062023-08https://hdl.handle.net/11299/256389Antibiotic resistance is an urgent global public health threat, as resistant bacteria can overcome antibiotic stress and grow despite treatment. In combination with another strategy of antibiotic failure, antibiotic persistence - which describes the survival of a tolerant subpopulation of bacterial cells, development of full resistance mutations may evolve faster. Bacteria tend to live in microbial communities, where they may participate in mutualistic ecological interactions as they exchange essential nutrients in a cross-feeding manner. Specifically in natural microbial communities, bacteria participate in spatially-structured, localized interactions on surfaces. How these microbial ecological factors affect the evolution of antibiotic persistence and resistance is unknown. Here, I studied the evolution of antibiotic persistence and resistance in Escherichia coli evolved in monoculture and in a synthetic cross-feeding mutualism with Salmonella enterica in structured habitats. After 16 cycles of cyclical exposure to short-term ampicillin treatment and drug-free growth on agar surfaces, evolutionary rate of persistence and subsequent resistance were analyzed. I found that while E. coli in the mutualistic coculture begins with high persistence, the monoculture persistence evolves at a faster rate. In contrast, E. coli in the spatially-structured mutualism evolves 3-fold higher resistance than the wild-type, while the monoculture counterpart does not. These results warrant further studies regarding the mechanism behind the differential evolution of antibiotic resistance between the mutualistic coculture and the monoculture.enPresentation