Evaluation of the biodegradation feasibility of antibiotics by three bacteria involving glutathione S-transferases

Abstract

Swine wastewater is not easy to dispose of in usual biological wastewater treatment plants. One reason is that some antibiotics are not easily degradable in the normal treatment system and suppress or inhibit microorganisms in the treatment system. Specifically tetracycline, sulfathiazole, and ampicillin have been widely used as antibiotics in pig feed. For treating disposal and spillage of these antibiotics biologically, a special enzyme based method is needed. Detoxifying enzymes caused the antibiotics to be bio-converted in this experiment and degraded them in this biological experiment. The glutathione S-transferases (GSTs) catalyzed the conjugation of glutathione (GSH) to a number of hydrophobic electrophilic substrates. In this study, we hypothesized that the microorganisms with GSTs degraded the representative manure antibiotics. The initial concentrations of tetracycline, sulfathiazole, and ampicillin were 100  mg/L, 100  mg/L, and 50  mg/L, respectively. These concentrations of antibiotics in pig feed are typical levels. Evaluation of the biodegradation feasibility of antibiotics was carried out by three bacteria possessing glutathione S-transferases under the strong concentration of antibiotics (standards for livestock pharmaceuticals in pig feed).