FIG. 3.

In situ hybridization of sections from mesophilic and thermophilic granules viewed by CLSM. The sections were simultaneously hybridized with Cy-5-labeled bacterial probe (EUB338) (green) and rhodamine-labeled probe for several phylogenetic groups of methanogens (red). (A to C) Mesophilic sludge granule sections; (D to F) thermophilic sludge granule sections. (A and D) Sections hybridized with MX825 probe for the genus Methanosaeta (red) and bacterial probe (green). (B and E) Sections hybridized with MB1174 probe for the family Methanobacteriaceae (red) and bacterial domain probe (green). The inset in panel B is a magnification of a microcolony of coccoid bacterial cells and Methanobacteriaceae. (C) Mesophilic section hybridized with MG1200 probe (red) for the order Methanomicrobiales and bacterial probe (green). (F) Thermophilic section hybridized with MS1414 probe (red) for the family Methanosarcinaceae and bacterial probe (green), indicating a microcolony of Methanosarcina-like organisms (inset).