The Deflocculating Enzyme Produced by a Floc-forming Bacterium

The bacterium strain No. 12 isolated from a phenol-adapted activated sludge as a floc-forming bacterium was found to produce an exoenzyme which could deflocculate its own floc. As the floc of this bacterium was not deflocculated with EDTA and various enzymes such as cellulase, protease, and lysozyme, this exoenzyme was isolated and purified. The optimal pH of the enzyme for deflocculation was 3.8 to 5.0, and the optimal temperature 30°. The enzyme was unstable at a high temperature, and heating at 45° for 5 min resulted in complete loss of the activity. The activity of the enzyme was inhibited by a relatively low concentration of salts, acidic and basic amino acids, uronic acids, and amino sugars. Purified preparation of this enzyme released sugars from the No. 12 floc during deflocculation, though it could not hydrolyze cellulose, pectin, and ethylene glycol chitin. These results indicate that the No. 12 floc is composed of some exopolysaccharides other than those so far reported and deflocculated only by the enzyme produced by the bacterium itself.