Decomposition of Antibiotics in Water Systems and the Impact on Microbial Communities

Faculty Sponsor

Dr. Julie Peller and Dr. Sara Dick


Arts and Sciences


Chemistry Department; Biology Department

Presentation Type

Poster Presentation

Symposium Date

Summer 7-28-2016


Penicillin is one of the most prescribed antibiotics for humans and animals. As a result, unmetabolized penicillin is discharged into water systems, and bacteria in those water systems become resistant. To better understand the lifetime of penicillin in water systems, the decomposition of Penicillin G (Pen G) in water solutions was studied. Simultaneously, the behavior of Staphylococcus aureus was analyzed. Four different 50 uM aqueous solutions of Pen G were studied, 1) water, 2)10 ppm Dissolved Organic Material (DOM), 3) 5mM NaHCO3, and 4) both DOM and NaHCO3. These solutions were analyzed weekly for 13 weeks using Ultra High Performance-Liquid Chromatography-Mass Spectrometry (UHPLC). Pure Pen G in water decomposed completely within two weeks. The solution containing NaHCO3 showed similar results, although decomposition was slower. The rate of decomposition of Pen G in the DOM solutions was even slower, as Pen G remained in solution after thirteen weeks. The same solutions of Pen G were used to test the susceptibility of the antibiotic on plates of S. aureus. The bacteria plates exposed to the Pen G and Pen G in NaHCO3 solutions showed that after time the antibiotic was less effective against the bacteria. The bacteria plates exposed to the Pen G in DOM solutions showed that the antibiotic was still effective against the bacteria. Pen G resistant colonies of the bacteria were found on almost all of the plates tested.

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