GROWTH OF PHANEROCHAETE-CHRYSOSPORIUM IN SOIL AND ITS ABILITY TO DEGRADE THE FUNGICIDE BENOMYL

Following inoculuation Phanerochaete chrysosporium grew faster across the surface of an agricultural loam soil at 37-degrees-C than when inc ubated at 25-degrees-C. Starch or peptone, alone or in combination, fa iled to stimulate growth of the fungus, while the addition of peptone or peptone-plus-starch to soil incubated at 25-degrees-C (but not at 3 7-degrees-C) stimulated a bacterium antagonistic to P. chrysosporium. The bacterium produced an antifungal agent in vitro, which inhibited t he growth of filamentous fungi including P. chrysosporium and the yeas t Candida tropicalis. The assumption that the addition of nutrients to soils necessarily stimulates growth and soil colonization by an inocu lated fungus is thereby questioned. Soil incubation with a spore suspe nsion of P. chrysosporium caused a 60% reduction in the time taken to completely degrade 56.25 mug of benomyl g-1 soil, and at least a 30%-p lus reduction in the time taken to completely degrade higher concentra tions. These results are discussed in relation to practical approaches to the bioremediation of benomyl-treated soils.