Comparison of Bacteria from Varied Soils with Potential Antimicrobial Activity

Comparison of Bacteria from Varied Soils with Potential Antimicrobial Activity

Alvin Sherman Library

Antibiotic resistance is increasing at a rate that surpasses the discovery and development of new antimicrobial compounds, creating a widening resistance-innovation gap that poses a global public health concern. To address this need for new antibiotic-producing organisms, we partnered with Tiny Earth, a global initiative that engages students in antibiotic discovery through soil sample collection, bacterial isolation, and antimicrobial screening. We isolated bacteria from local soil in Davie, Florida as well as soil from the White River Badlands, South Dakota with the hypothesis that distinct soil conditions may yield different antimicrobial producers with varied activity and chemical profiles. 42 unique soil bacteria were isolated and screened for antimicrobial activity against safe relatives of clinically relevant pathogens (ESKAPE pathogens). Zones of inhibition were observed for the Davie and Badlands soil isolates when screened against the safe relatives Bacillus subtilis, and Escherichia coli, respectively. All inhibitory isolates underwent phenotypic and molecular characterization, including Gram staining, enzymatic testing, 16S rRNA gene sequencing, taxonomic identification using the BLAST database, and biosynthetic gene cluster identification using the bacterial antiSMASH database. One isolate from the Davie soil matched the genus Acinetobacter and one Badlands isolate matched the genus Peribacillus. A second Davie isolate produced a 16S rRNA sequence with no match in the BLAST database, indicating a potentially novel or highly divergent bacterium with underexplored activity against Gram-positive bacteria. Further genomic and chemical analyses will be performed to clarify the identity of these isolates and the antimicrobial compounds produced by them.