PURPOSE: To propagate microorganisms for decomposing humic acid by culturing basidiomycetes with culture soln. of 5-7pH while utilizing saccharides as a main carbon source under the aerobic conditions by strong agitation and thereafter performing culture by weak agitation and furthermore performing propagation of the pellets while utilizing hypha as a nucleus.

CONSTITUTION: A culture soln. of 5-7pH is prepared while utilizing saccharides as a main carbon source and basidiomycetes of the genera Myrothecium, Pleurotus and Coriolus having performance capable of decomposing humic acid by this culture soln. are dispersed and propagated by performing culture by strong agitation under the aerobic conditions. Then microorganisms for decomposing humic acid are propagated by performing culture by weak agitation and furthermore performing propagation of the pellets while utilizing dispersed hypha as a necleus. The settling velocity of bacteria is made speedy and dispersibility can be held by forming large quantities of small pelletlike bacteria by such a way.