Methanogens revealed immunologically in granules from five Upflow Anaerobic Sludge Blanket (UASB) bioreactors grown on different substrates
Methanogens were identified and quantified using antibody probes and the antigenic fingerprinting method in five different kinds of granular sludge taken from five Uplow Anaerobic Sludge Blanket (UASB) bioreactors maintained on different substrates. The methanogenic flora present in each bioreactor was elucidated and expressed in cells per garm dry weight. Autofluorescence, phase-contrast and bright field-microscopy of unstained and Gram-stained preparations were used in parallel with immunotechnology to characterize each methanogenic subpopulation. Ten different methanogens were prevalent in the five bioreactor systems. Methanogens antigenically related to Methanobacterium formicicum MF, Methanobrevibacter arboriphilus AZ and Methanothrix soehngenii Opfikon were found in all five granules, while other methanogens were present in only some. A trend was observed towards a wider diversity of methanogenic subpopulations parallelling an increase in the complexity of the bioreactor's substrate.