Fighting Antibiotic Resistance: Antibiotic Activity from Local Californian Soil

The antimicrobial resistance (AMR) crisis is a prevailing problem in the healthcare industry; in 2019 alone, 1.27 million deaths were directly caused by AMR infections around the world. In our efforts to address this global issue, the Carlson laboratory has collaborated with local high school students during the Medical Microbiology program in Pacific’s Summer High School Institute (PSHSI). Using the Tiny Earth curriculum from the University of Wisconsin-Madison (UWM), two cohorts of high schoolers have screened bacteria from soil samples collected across California. During spring break of 2023 and 2024, soil was collected and treated to grow a diversity of bacteria on “diversity plates.” The high school students learned about isolating bacteria and made some of their own diversity plates from soil collected on campus. In the fall, we (undergraduate researchers) plated and screened all 275 isolates identified during the summer institute. We confirmed their observations by retesting these isolates for inhibition of four human pathogens, Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Salmonella sp.. From these assays, pathogen-inhibiting isolates were uploaded to the global Tiny Earth Database (tinyearth.com), and agar slants of these cultures were sent to UWM for further genomic characterization and metabolic testing for their potential to produce new antibiotics. We are currently restarting the cycle with new soil samples for this summer's institute. New diversity plates will be created in search of new antibiotic producing isolates to combat the AMR crisis.