Abstract
The microbial community structures present in the thermophilic anaerobic digestion (TAD) of waste-activated sludge (WAS) and WAS were analyzed with molecular biological techniques including polymerase chain reaction-denature gradient gel electrophoresis (PCR-DGGE), real-time PCR, and cloning analysis. No significant differences in the microbial community structures present in TAD were observed among three reactors operated with hydraulic retention times of 10, 20 and 30 days. The microbial community present in TAD had less diversity than that present in WAS, and the sequences obtained in WAS were not present in TAD by the cloning analysis. In the TAD bacterial clone library, 97.5% of the total clones belonged to Firmicutes and 73.1% belonged to Coprothermobacter. Real-time PCR and cloning analyses revealed that the number of Methanosarcina thermophila, which is an acetoclastic methanogen, was larger than that of Methanoculleus thermophilus, which is a hydrogenotrophic methanogen, in terms of the numbers of copies of 16S rDNA.
