The influence of six pharmaceuticals on freshwater sediment microbial growth incubated at different temperatures and UV exposures

Pharmaceutical compounds have been detected in freshwater for several decades. Once they enter the aquatic ecosystem, they may be transformed abiotically (i.e., photolysis) or biotically (i.e., microbial activity). To assess the influence of pharmaceuticals on microbial growth, basal salt media amended with seven pharmaceutical treatments (acetaminophen, caffeine, carbamazepine, cotinine, ibuprofen, sulfamethoxazole, and a no pharmaceutical control) were inoculated with stream sediment. The seven pharmaceutical treatments were then placed in five different culture environments that included both temperature treatments of 4, 25, 37A degrees C and light treatments of continuous UV-A or UV-B exposure. Microbial growth in the basal salt media was quantified as absorbance (OD550) at 7, 14, 21, 31, and 48d following inoculation. Microbial growth was significantly influenced by pharmaceutical treatments (P < 0.01) and incubation treatments (P < 0.01). Colonial morphology of the microbial communities post-incubation identified selection of microbial and fungal species with exposure to caffeine, cotinine, and ibuprofen at 37A degrees C; acetaminophen, caffeine, and cotinine at 25A degrees C; and carbamazepine exposed to continuous UV-A. Bacillus and coccus cellular arrangements (1000X magnification) were consistently observed across incubation treatments for each pharmaceutical treatment although carbamazepine and ibuprofen exposures incubated at 25A degrees C also selected spiral-shaped bacteria. These data indicate stream sediment microbial communities are influenced by pharmaceuticals though physiochemical characteristics of the environment may dictate microbial response.