Effects of Macrolide Antimicrobials on the Performance of Anaerobic Treatment Systems
An anaerobic sequencing batch reactor (ASBR) was operated to study the effects of tylosin, a macrolide antimicrobial commonly used in swine production, on treatment performance and the development of antimicrobial resistance. The addition of 1 mg/l tylosin to the reactor had no effects on the biogas production and chemical oxygen demand (COD) removal efficiency. Specific methanogenic activity (SMA) batch tests showed a significant (p < 0.05) decrease of the maximum methane production rate in the presence of 100 mg/l of tylosin for the substrate acetate and 1 mg/l and 100 mg/l of tylosin for the substrates propionate and butyrate. Tylosin addition to the ASBR would affect the utilization of acetate, propionate, and butyrate. Tylosin may exert inhibitory effects on saturated fatty acid beta-oxidizing syntrophic bacteria and gram-positive homoacetogenic bacteria.