UNSPECIFIC DEGRADATION OF HALOGENATED PHENOLS BY THE SOIL FUNGUS PENICILLIUM-FREQUENTANS-BI-7 2/

Resting phenol-grown mycelia of the fungus Penicillium frequentans str ain Bi 7/2 were shown to be capable of metabolizing various monohaloge nated phenols as well as 3,4-dichlorophenol. 2,4.dichlorophenol could be metabolized in the presence of phenol as cosubstrate. In the first degradation step the halogenated phenols were oxidized to the correspo nding halocatechols. Halocatechols substituted in para-position (4-hal ocatechols) were further degraded under formation of 4-carboxymethylen but-2-en-4-olide. A partial dehalogenation took place splitting the ri ng system. 3-Halocatechols were cleaved to 2-halomuconic acids as dead end metabolites without a dehalogenation step. Dichlorophenols were o nly transformed to the corresponding catechols. In addition 3,5-dichlo rocatechol was O-methylated to give two isomers of dichloroguaiacol. T he halogenated catechols with the exception of 4-fluorocatechol partly polymerized oxidatively in the culture fluid to form insoluble dark-b rown products. The degradation of halophenols are due to the action of unspecific intracellular enzymes responsible for phenol catabolism (p henol hydroxylase, catechol-1,2-dioxygenase, muconate cycloisomerase I ).