Functional genes were quantified to demonstrate the inhibitory effect of SMX on particular physiological prokaryotic groups, especially methanogens. For this purpose, three metabolic genes were selected to detect the inhibition effect of SMX on the homoacetogenesis, methanogenesis and, specifically, acetoclastic methanogenesis pathways;
formyltetrahydrofolate synthetase (FTHFS), methyl-coenzyme M reductase (mcrA) and acetyl-coA synthetase (ACAS), respectively. Inhibition effects were determined by an mRNA-based approach