Effect of Mucor alternans on the persistence of DDT and Dieldrin in culture and in soil.

Abstract

Several fungi were isolated from an agricultural loam soil and tested for their capacity to degrade the insecticides DDT or dieldrin. It was found that Mucor alter nans van Tieghen in shake cultures partially degraded DDT within 2 to 4 days into 3 hexane-soluble and 2 water-soluble metabolites. None of these compounds had R1 valutes that were identical to those observed with DDD (TDE), DDE (1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene), DDA (bis-(p-chlorophenyl) acetic acid), DBP (4,4´-dichlorobenzophenone), dicofol, and 1,1-bis (p-chloropbenyl) ethane. After application of C14-DDT, 42% of the totally recovered radioactivity was represented by the 2 water-soluble metabolites. Some indication of dieldrin breakdown by the fungus was evident, but no metabolites could be isolated. Degradation of both DDT and dieldrin occurred only with live fungi mycelia, while the insecticides were passively absorbed to dead mycelial controls. After the addition of M. alternans spores to a DDT- or dieldrin-contaminated agricultural loam soil, the insecticide degrading capacity of the fungus was no longer evident. This result was rather disappointing since a need exists to be able to degrade persistent pesticides in nature with soil microorganisms. Since DDE was only found in nonautoclaved soils, its formation from DDT was a function of soil microorganisms.