Quantification of methanogen cell density in anaerobic granular sludge consortia by fluorescence in-situ hybridization.

Whole cell fluorescence in-situ hybridization (FISH) with 16S rRNA targeted oligonucleotides was applied to reveal the microbial ecological structure of UASB-grown granular sludge. The FISH analysis indicated that the members of the domain Archaea accounted for 28 to 53% of the total cells in various granular sludge sources, while Methanosaeta and Methanobacteriaceae cells accounted for 13 to 38%, and 4 to 27%, respectively. Methanosaeta cell density and Methanobacteriaceae cell density were strongly correlated, respectively, with acetate-utilizing methane production activity and with hydrogen-utilizing methane production activity. [ABSTRACT FROM AUTHOR]