Dynamics of transitional acidogenic community along with methanogenic population during anaerobic digestion of swine wastewater

The changes in bacterial communities associated with volatile fatty acids (VFAs) profiles were investigated in anaerobic batch reactors treating swine wastewater. Denaturing gradient gel electrophoresis and real-time PCR were used to analyze the bacterial community structure and the methanogenic population, respectively. The three subspecies of Lactobacillus delbrueckii (bulgaricus, lactis, and indicus) along with the Clostridium-like organisms were identified. The L. delbrueckii-related organisms were assumed to be responsible for the fermentation of the organic compounds throughout the overall reaction period. The presence of Clostridium ultunense and Clostridium kluyveri, together with hydrogenotrophic methanogens, was essential for methane production from propionic acid in the later stage of the experiment. Our results show that the variations in VFA concentrations and methane production were complex and dynamic. We also demonstrate that an analysis of the acidogenic community, together with the methanogenic population, is essential for developing insight into the anaerobic digestion of swine wastewater.