The effect of electrostatic and hydrophobic properties of microorganisms in anaerobic sludge on the immobilization onto support materials was experimentally studied. As a result, Methanosaeta concilii which is the most popular aceticlastic methanogen was electrically neutral and hydrophobic. Methanosarcina barkeri of a methyltrophic methanogen and acidogens cultivated selectively from the anaerobic sludge were negatively charged and hydrophobic. In addition, the immobilized microorganisms on support materials were incubated with sodium acetate. It was found that the methanogens were significantly immobilized onto bamboo charcoal in contrast to hydrophilic alumina. It was also shown that Methanosaeta-like microorganism is immobilized to bamboo charcoal. These experimental results suggest that the hydrophobic and negatively charged support material is suitable for the selective immobilization of Methanosaeta sp., which is the most important microorganism in the methane fermentation, by suppressing the immobilization of the microorganisms other than Methanosaeta sp.
