Assessing the Impact of Media on Antibiotic Production

Student Classification


Faculty Mentor

Dr. Misty Thomas



Document Type


Publication Date

Spring 2019


The antibiotic crisis has come about due to the amount of antibiotics used, soon resulting in antibiotics that will no longer work to treat bacterial infections. When bacteria can no longer be killed by antibiotics, it is called antibiotic resistance and it is the cause of the antibiotic crisis. ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species, and Mycobacterium tuberculosis) are at the forefront of the antibiotic resistance crisis. The ability of soil bacteria to produce antibiotics against ESKAPE pathogen safe relatives (Escherichia coli, Staphylococcus epidermidis, Enterobacter aerogenes, Acinetobacter baylyi, Mycobacterium smegmatis, Bacillus subtilis, Enterococcus raffinosus, and Pseudomonas putida) on different types of agar was tested. It was predicted that if the antibiotic-producing soil bacteria are placed on different types of media, then it will affect their production of antibiotics because different media offers different nutrients for growth and bacteria do not typically grow the same on different types of media. Bacteria was isolated via serial dilutions of soil samples from various locations. Each isolate was plated with each ESKAPE pathogen safe relative on Luria-Bertani Agar (LBA), Reasoner’s 2A Agar (R2A), Trypticase Soy Agar (TSA) and Potato Dextrose Agar (PDA) plates and their ability to produce an antibiotic was observed. Antibiotic production was measured by the millimeters of growth clearance between the isolates and the ESKAPE relatives. In the results of the experiment, the bacteria did produce varying amounts of antibiotics depending on what media it was plated on. Overall, the soil bacteria produced the most antibiotics on LBA and the least antibiotics on PDA. This directly corresponds to the bacteria's ability to grow on each media. This study shows that the media that is used does have an effect on a bacteria's ability to produce an antibiotic.

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