BIODEGRADATION OF 3 SUBSTITUTED PHENYLUREA HERBICIDES (CHLOROTOLURON,DIURON, AND ISOPROTURON) BY SOIL FUNGI - A COMPARATIVE-STUDY

As a part of a study conducted on the fate of xenobiotics in the envir onment, a selection of 90 strains of micromycetes, mostly isolated fro m soil and belonging to various taxonomic groups, have been cultivated In liquid synthetic medium with chlortoluron (100 mg.L(-1)), diuron ( 20 mg.L(-1)), and isoproturon (100 mg.L(-1)) for 5 days. Evaluation of the chemicals in the culture media was made by HPLC. Our results show a wide variation not only with taxonomic groups but also with the spe cies, and with the tested chemicals. On the whole, 4, 7, and 11% of th e strains depleted respectively chlortoluron, diuron, and isoproturon, at 50% or over. Rhizoctonia solani was the only strain that depleted each of the 3 substituted phenylureas over 70%, nevertheless, the grow th of this fungus was slightly inhibited by diuron. The very fast desa ppearance of the chemicals from the culture media was only due to biot ic phenomena, as no adsorption occurred on the fungal biomass. So, dep letion translated a real biodegradation of the tested substrates. Copy right (C) 1996 Elsevier Science Ltd