Enhanced biomethanation with acid stress on anaerobic sludge, dehydrogenase activity, protein expression, and the primary proteomic profiling of microbial communities during the enhanced anaerobic digestion process from Taihu Blue Algae were investigated. It was found that the accumulation of organic acids and the specific biogas accumulation rate were 1.8 and 1.3 times of the control, when 10 g/L and 7.5 g/L of butyrate were selected for acid stress, respectively. Meanwhile, dehydrogenase activity of the 7.5 g/L acid stress group exhibited an increase of 1.6 times of the control, and protein expression was also found to be enhanced sharply as revealed by 1D-PAGE. Finally, twenty of the matched protein spots through 2D-PAGE from both the control and the 7.5 g/L stress groups were identified by MALDI-TOF MS, and five of which were proved to be involved in bioenergy metabolism. Significantly, ATR related proteins might be induced as the p/s of which were acidic as 5.92, 5.51 and 5.54, respectively. (C) 2012 Elsevier B.V. All rights reserved.