The Effect of Media-Type on Antibiotic Production

Student Classification


Faculty Mentor

Misty Thomas, Ph.D.


Department of Biology

Document Type


Publication Date

Spring 2019




Background: There has been little done to combat the antibiotic crisis in the past 30 years. The diminishing antibiotic production is due to bacteria's rapid resistance to the antibiotics. Bacterial resistance is due to the overuse and abuse of antibiotics within agriculture and human welfare. Pharmaceutical companies reject funding to support new antibiotic production, that ordinarily become ineffective after a few years of manufacturing. It is predicted that there will soon be no antibiotics to combat even the simplest bacterial infections. The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species, and Mycobacterium tuberculosis) are most commonly associated with nosocomial infections and contribute to the antibiotic crisis. The goal is to find potential bacteria capable of combating the ESKAPES. Soil bacteria have been included in the antibiotic production in the past. We have 32 bacteria isolates derived from soil capable of antibiotic production, in hopes to find the effect of media on the antibiotic production. Hypothesis: We hypothesize that if isolates are placed on different media, then antibiotic production will be affected as diverse responses will be observed, because different media provides different nutrients altering antibiotic production. Methods: The ability of soil bacteria to produce antibiotics against ESKAPE pathogen safe relatives on different types of agar was tested. Bacteria were isolated via serial dilutions of soil samples from various locations. Each isolate was picked and patched onto swab plates of the ESKAPE relative on one of Luria-Bertani Agar (LBA), Reasoner’s 2A Agar (R2A), Trypticase Soy Agar (TSA) and Potato Dextrose Agar (PDA) and their ability to produce an antibiotic was assessed by characterization of zones of inhibitions. After analysis, 32 producing isolates were selected for their ability to produce an antimicrobial agent on one type of agar and subsequently plated on all 4 types of media to assess the changes in zones of inhibition on each media type. Results/Conclusion: In conclusion, media type has a significant impact not only on antibiotic production for the tested soil isolates, but also on the amount of antibiotic activity and on which escapes are susceptible. Significance: To find potential antibiotics from bacteria derived from soil to combat the ESKAPES and antibiotic crisis. To present the affects of media selection on antibacterial production. To find the most optimal media for antibiotic production for different isolates.

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