Abstract
Microorganisms capable of lysing filamentous bacteria were isolated from activated sludge by screening for their ability to form plaques on an agar plate seeded with cells of Sphaerotilus natans. The supernatant obtained by culturing of those microorganisms lysed S. natans in a liquid culture. Nine strains in the isolated microorganisms revealed very strong lytic activity. The surpernatants were capable of lysing S. natans, Type 021N and Type 1701. However, Type 0041 and Nocardia were not lysed. After purification using column chromatography followed by anion-exchange, gel-filtration and hydroxyapatite chromatography, the lytic substance produced by B. polymyxa showed the highest lytic activity in all of screened bacteria. However, a specific band representing the substance responsible for the lytic activity could not be observed.
