Abstract
Adhesion and coaggregation phenomena of acetate-utilizing methanogens in the methane fermentation process were examined. The surface characteristics of three acidogens enriched from the anaerobic sludge and the pure cultures of Methanosarcina barkeri and Methanosaeta concilli were estimated. As a result, the selective adhesion phenomena of acetate-utilizing methanogen onto the bamboo charcoal could be explained by the electrostatic interaction and the change of free energy of interaction between microbes and support materials. The non-washed proteolytic bacteria and Methanosarcina barkeri were found to coaggregate rapidly even though the change of free energy of interaction was positive. It is guessed that these two microbes coaggregate with biological interaction because proteolytic bacteria produce hydrogen which is the substrate of Methanosarcina barkeri. The proteolytic bacteria enriched in this study can be expected to be used as bioflocculant that rapidly forms the granule of acetate-utilizing methanogens.
