Methane-producing archaea (MPA) and sulfate reducing bacteria (SRB) are common microorganisms in the anaerobic system. However antimicrobials may directly inhibit biological activities or even deteriorate and collapse anaerobic processes (Ji et al.,2013). During laboratory-scale experiments, a 27.8% reduction of methane production has been observed with 28 mg L1 chlortetracycline, while methane production decreased to 6.2 L d1 from 6.8 L d1 as a result of inhibition by 200 mg L1 ERY (Amin et al.,2006). However, in the existing literature, there are only a limited number of studies investigating the influence of antimicrobials on microorganisms, and most of that research only paid attention to the effect on methanogenesis and neglected effects on sulfate reducing bacteria