Spatial succession and metabolic properties of functional microbial communities in an anaerobic baffled reactor

The spatial successions of bacterial and archaeal communities in anaerobic digestion were investigated in a glucose-degrading five-compartment anaerobic baffled reactor (ABR). The distributions of H-2-producing acetogens, H-2-utilizing acetogens and methanogens in different anaerobic-digestion stages were quantitatively analyzed using functional probes. The results show that the acidogenesis stage and acetogenesis stage were located in the first two compartments, while the methanogenesis were located in the last two compartments. In acidogenesis/acetogenesis stage of anaerobic digestion, H-2-producing acetogens (19.7%) and H-2-utilizing acetogens (8.3%) were the dominant bacterial community. While in methanogenesis stage, methanogens became the dominant (40.2%) with H-2-producing acetogens and H-2-utilizing acetogens only accounting for 6.6% and 4.8%, respectively. With the bacterial population decreasing from 7.2 +/- 0.5 x 10(12) cells mL(-1) to 0.6 +/- 0.3 x 10(12) cells mL(-1) along water flowing direction, their diversity increased from 2.79 to 299. The acidogenic bacteria, such as Lactococcus sp., Uncultured Firmicutes bacterium, and Uncultured Clostridium sp., etc., dominated in the acidogenesis/acetogenesis stage, while Uncultured Desulfobacterales bacterium became dominant in the methanogenesis stage. A two-stage anaerobic process may be suitable for easily degradable organic matters removal. (C) 2013 Elsevier Ltd. All rights reserved.