Effect of classic methanogenic inhibitors on the quantity and diversity of archaeal community and the reductive homoacetogenic activity during the process of anaerobic sludge digestion

In this study, the microbial response of anaerobic sludge digestion to the addition of two classic methanogenic inhibitors (chloroform, 2-bromoethanesulfonate) was investigated. Both the toxicants showed their effectiveness on CH4 production, whereas the hydrogen responses and acetate accumulations were elicited to different extent. Terminal restriction fragment length polymorphism analyses in combination with clone library showed that both toxicants inhibited not only methanogenic activity but the structure of methanogenic communities. The acetoclastic Methanosaetaceae was more sensitive than hydrogenotrophic Methanobacteriales and Methanomicrobiales. Interestingly, as reflected by the favorable thermodynamic condition and the increase of formyltetrahydrofolate synthetase (fhs) gene copy numbers, reductive homoacetogenesis from H2/CO2 was also stimulated by selective inhibition of methanogenesis with 2-bromoethanesulfonate (BES).