The results of this study show that the inhibitory effect of antimicrobials on MPA caused a reduction in SMA activity of less than 50%. These results indicate that a significant portion of the SMA within the granular sludge can be maintained even in the presence of measurable amounts of antimicrobials. The different resistance to antimicrobials between archaea and bacteria depends on their different cellular structures. The peptidoglycan in cell walls is the action site for CLX, and methanogenic archaea do not have this cellular feature. Compared with bacterial ribosomes archaeal ribosomes
have a heterogeneous protein composition to adapt to harsh environmental conditions (Hilpert et al., 1981). Thus MPA exhibited more tolerance than SRB when ERY or TC inhibited its protein synthesis. The sulfonamides are bacteriostatic inhibitors designed to prevent bacterial infections and thus reveals a more obvious effect on bacteria than archaea (Perlin, 2011).