Among 194 bacterial strains isolated from three representative sludge samples, 14 strains, which could produce efficient MBF, were obtained after screening and re-screening. These MBF had shown positive effects on treatment of four kinds of selected wastewater. However, after examining the hereditary stability of flocculation activity for bacteria, most of the strains lost their ability in producing effective MBF except for the I-41 strain. The I-41 is a bacillus G + amphibacterium. Meanwhile, the model of MBF-producing bacteria is found in this trail program.