Environmental chemistry of PCB-replacement compounds - V - the metabolism of chloro-isopropylbiphenyls in fish, frogs, fungi and bacteria

Abstract

The metabolism of 2,5-dichloro-4'-isopropylbiphenyl and 4-chloro-4'-isopropylbiphenyl, two model compounds for alkylated chlorobiphenyls (Chloroalkylenes), has been investigated in fish, frogs, fungi and mixed cultures of bacteria. Fish (Carassius auratus) and frogs (Rana aesculenta) show a very limited metabolism of these compounds. A pure strain of fungus (Cunninghamella echinulata Thaxter) metabolized 2,5-dichloro-4'-isopropylbiphenyl both by stepwise oxidation of the isopropyl group to 2,5-dichloro-4'-biphenylcarboxylic acid and by hydroxylation of the chlorine substituted phenyl ring. A mixed culture of aerobic bacteria from activated sludge shows extensive degradation of 4-chloro-4'-isopropylbiphenyl to p-chlorobenzoic acid via stepwise oxidation of the isopropyl group when using the compound as sole carbon source. However, in the presence of D-glucose as additional carbon source, no metabolism is observed.