The effect of tetracycline on the structure of the bacterial community in a wastewater treatment system and its effects on nitrogen removal

Abstract

This study examined the impact of tetracycline at two environmentally relevant concentrations (1 μg/L and 10 μg/L) and one synthetically high concentration (500 μg/L) on the structure and function of the microbial community from the secondary treatment process of a municipal wastewater treatment plant (WWTP). Specifically, this study examined whether the introduction of tetracycline into bench scale reactors at two different replacement volume rates would cause a shift in the composition profile of the bacterial community. Furthermore concentrations of ammonia, nitrate/nitrite and total Kjeldahl nitrogen were monitored to examine the effect of the antibiotic on ammonia and nitrogen removal. At the low volume replacement rate, tetracycline was observed to have a positive impact on nitrogen removal. Total Kjeldahl nitrogen concentrations were also observed to decrease suggesting a role for tetracycline as a carbon source. However, at the higher volume replacement rate, the removal of ammonia and nitrogen were not significantly different from reactors that did not contain tetracycline. Over time, the bacterial composition profiles changed under all the conditions studied, however, the bacterial composition profiles appeared to be more influenced by the replacement volume rate than the presence of tetracycline even at concentrations many times higher than environmentally relevant amounts.

Keywords: Ammonia; Microbial community profiles; Nitrogen; Tetracycline; Wastewater.