Presenter: Helena Klein
Faculty Mentor: Karen Guillemin, Cathy Robinson
Presentation Type: Poster 72
Primary Research Area: Science
Major: Biology
Bacteria have rapid growth rates, which allow us to study their adaptive evolution in the lab to selected environments. By studying the genetic changes that occur during the evolutionary process, we can learn about selective pressures experienced by bacteria when evolved in selected conditions. Through passaging of a strain of a natural zebrafish gut isolate, Aeromonas ZOR0001, we isolated one strain that has increased pigmentation compared to the wildtype. This pigmentation is a result of accumulation of pyomelanin in the extracellular environment. We confirmed through genetic sequencing a mutation in the isolate’s metabolic pathway known to be involved in pyomelanin production. Pyomelanin production has been shown in other organisms to be linked to increased resilience to oxidative stress. Therefore, we hypothesized this mutation confers a fitness advantage to this evolved isolate compared to the ancestral strain. Therefore we generated a genetic knockout of the mutated gene in the ancestral strain and used hydrogen peroxide to simulate oxidative stress in vitro. We found that the knockout strain did better than the wild type strain. This demonstrates that pyomelanin production confers resistance to oxidative stress in Aeromonas ZOR0001 which suggests an adaptive advantage for in vivo growth. Knowledge of genes that increase fitness in bacterial strains in the gut can ultimately allow for better probiotics to be developed with wide repercussions for human health.