Tobramycin resistance is less likely to evolve under nitrogen limitation.

I am investigating whether nutrient-limited environments impact the evolution of antibiotic resistance in Escherichia coli. We evolved E. coli for 24 days in nitrogen- or carbon-limited environments with and without tobramycin. Nitrogen-limited populations were less likely to evolve antibiotic resistance as many went extinct before day 24. Growth curves for the evolved and ancestral populations showed that tobramycin-resistant populations grew more slowly than the ancestor in the absence of antibiotics. I also conducted fitness assays to evaluate the competitive ability of the evolved populations compared to their ancestor.