FLOC-FORMING BACTERIA ISOLATED FROM ACTIVATED SLUDGE

Abstract

Various floc-forming bacteria isolated from activated sludge were found to form capsular matrix or extracellular fibrils around the cells. Such extracellular materials were susceptible to cellulase, pectinase, or protease, and deflocculation was observed after treatment by these enzymes. The cellulase- susceptible floc-forming bacterium was identified as Bacillus cereus. while the protease-susceptible one was identified as Flavobacterium dormitator which has not been observed as a floc-former thus far. Among the isolated bacteria, Corynebacterium fascians was also identified as a new floc-former. It is postulated that the extracellular polymers are responsible for the flocculent growth habit of bacteria.