[Study on microbial community in methanogenic granular sludge by FISH and DGGE]

Four methanogenic granules taken from an anaerobic reactor in different periods were investigated by FISH and DGGE, the eubacterial and archaeal community in these granules was researched and the phylogenetic analysis of dominant archaea was also studied. The FISH results indicated that the quantity of eubacteria was much more than archaea in the methanogenic granule and most eubacteria were located in the out layer of granule, while most archaea were located in the inner layer. The DGGE fingerprints indicated that as the organic loading rate of the reactor increased and the operating time elapsed, the eubacterial community was kept stable relatively, while the archaeal community was changed significantly, which resulted in the gradual decrease of the archaeal varieties. As seven typical bands were cut and sequenced, the results indicated that the dominant species of archaea in granule of the last period were Methanocor pusculum, Methanobacterium, Methanosaeta, and etc.