초록
<P><B>Abstract</B></P> <P>In this study, changes in the microbial communities and the metabolic pathway involved in anaerobic digestion were examined as the temperature was changed from 9 to 55 °C. The results from six batch biogas reactors, which were designed to ferment at 9, 15, 21, 35, 45 and 55 °C, showed that: 1) The components of the microbial communities and metabolic pathways were found to be very similar but the metabolic activities increased significantly when the temperature grew from 15 to 35 °C. 2) Hydrogenotrophic metabolism was almost exclusively observed when the temperature was lowered to 9 °C, whereas greater bacterial diversity involving hydrolisis, acidogenesis, and acetogenesis was observed when the temperature was raised to 45 °C. Finally, these dominant bacteria involved in hydrolisis, acidogenesis, and acetogenesis decreased in number when the temperature was raised to 55 °C and acetotrophic-type metabolism became the major metabolic pathway. That means the turning point for microbial community composition and metabolic pathway from mesophilic to thermophilic was at 45 °C and the metabolic pathway at 9 °C was somewhat different to those observed at 15–35 °C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microbial community structures were connected to their metabolic pathways. </LI> <LI> Microbial communities were similar but metabolic activity increased with temperature grew. </LI> <LI> Turning point for metabolic pathway from mesophilic to thermophilic was at 45 °C. </LI> <LI> Key microorganisms from hydrolysis to methanogenesis comprised not more than 20 species. </LI> </UL> </P>