Joan Slonczewski, Professor of Biology, has published an article, “Extreme Acid Modulates Fitness Tradeoffs of Multidrug Efflux Pumps MdtEF-TolC and AcrAB-TolC in Escherichia coli K-12” with Samantha Schaffner ‘21 and Abby Lee ‘22, along with12 other Kenyon College students/alumni. The article appears in the June 2021 issue of Applied and Environmental Microbiology.
Antibiotics and other drugs that reach the gut must pass through stomach acid. Yet little is known of how extreme acid modulates the effect of drugs on gut bacteria. We find that extreme-acid exposure leads to a fitness advantage for a multidrug pump that otherwise incurs a fitness cost. At the same time, extreme acid amplifies the effect of salicylate selection against multidrug pumps. Thus, organic acids and stomach acid could play important roles in regulating multidrug resistance in the gut microbiome. Our flow cytometry assay provides a way to measure the fitness effects of extreme-acid exposure to various membrane-soluble organic acids including plant-derived nutrients and pharmaceutical agents. Therapeutic acids might be devised to control the prevalence of multidrug pumps in environmental and host-associated habitats.