Utilizing dairy farm isolates to discover novel antibiotic-producing bacteria

Almost a century since the discovery of the first naturally occurring antibiotic to be used in a clinical setting, penicillin, in 1928, antibiotics have proven to be one of the most important medical interventions created. However, over time bacterial species have adapted and resisted antibiotics used to target them. Through evolutionary mechanisms, bacteria have developed many strategies for surviving or even thriving in the presence of antibiotics. One group of bacteria is causing major concern because of their virulence and resistance to the most common antibiotics: the ESKAPE pathogens. ESKAPE is an acronym for six types of bacteria including Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. The goal of this research was to identify antibiotic-producing dairy farm-associated bacterial isolates that were effective against ESKAPE and related pathogens. One such isolates “#24,” a strain of Bacillus subtilis produced zones of inhibition against six of the pathogens utilized in this research: E. faecium, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, and a non-ESKAPE pathogen Bacillus cereus. A second isolate “#23” was also analyzed against these ESKAPEs and related pathogens. Presumptive species identification indicates isolate #23 to be Bacillus cereus. Purification and analysis of isolate #24 reveal specific compounds that are capable of inhibiting the growth of pathogenic bacteria. This work will move us closer to having specific bacterial metabolites that show promise for use as chemotherapeutics against some of the most problematic multi-drug-resistant pathogens known and will address the global crisis of antimicrobial resistant (AMR) bacteria.