2023 63 B3

Isolating Antimicrobial Producing Bacterial Strains from Soil

By: Michael Gaerlan, Juan Carlos Gomez

Department: Biology

Faculty Advisor: Dr. Brinda Govindan

The emergence of antimicrobial-resistant bacteria is a serious global health issue. In 2019, 1.27 million people died due to antibiotic-resistant bacteria (Thompson, 2022). The widespread use, overuse, and misuse of antibiotics in medical treatments and agriculture have been the leading cause of increases in antibiotic-resistant bacterial infections. Finding novel antibiotics to treat resistant gram-negative infections is important since there are few drugs in our arsenal that can combat them. Our study aims to discover possible antibiotic-producing bacteria in natural environments such as soil. In our study, we isolated bacterial samples from three environments and performed a growth inhibition assay on nine safe relatives of pathogenic bacteria: Staphylococcus saprophyticus, Proteus mirabilis, Serratia marcescens, Citrobacter freundii, Escherichia coli, Enterobacter aerogenes, Staphylococcus epidermidis, Staphylococcus aureus, and Bacillus subtilis. One of our previous isolates (GH3) is a species of Pseudomonas that is typically found in soil. This particular strain inhibited the growth of three gram-negative bacteria: Proteus mirabilis, Enterobacter aerogenes, E. coli, and one gram-positive bacteria Staphylococcus saprophyticus. Two of our other unknown isolates (Omega B and GHD) also displayed positive inhibition against P. Mirabilis, Bacillus subtilis, and Enterobacter aerogenes. This project will contribute to the Tiny Earth Partnership Initiative in crowd-sourcing the discovery of novel antibiotics.