Conversion rates of five polycyclic aromatic hydrocarbons in liquid cultures of fifty-eight fungi and the concomitant production of oxidative enzymes

Fifty-eight fungi from different physio-ecological groups were compared for their capacity to oxidize five polycyclic aromatic hydrocarbons (PAH) with three to Eve benzene rings (R), and produce the appertaining extracellular oxidoreductases in liquid culture. In 14 d, wood- and straw-associated bas idiomycetes converted 19-90% of the original PAH compounds. The groups of w ood- and straw-degrading, wood-degrading, terricolous, ectomycorrhizal, and mitosporic fungi converted PAH at a proportion of 100:75:34:19:18. All fun gi preferred fluoranthene and pyrene (4R). Anthracene (3R) was preferred by wood-associated fungi. Phenanthrene (3R) and perylene (5R) were sufficient ly converted by wood-associated and terricolous, but poorly by ectomycorrhi zal and mitosporic fungi. Nevertheless, fungi that converted the entire set of PAH satisfactorily were found in all five groups PAH conversion was cor related with the production of manganese peroxidase (r = 0.98), peroxidase (r = 0.89), and laccase (r = 0.85), but not with monophenol monooxygenase ( r = 0.07). Mn(III) ions oxidized all PAH with preference to anthracene. Hyd rogen peroxide converted PAH possibly by the products of Fenton's reaction. Limiting factors were shortages in peroxidases and H2O2. Gymnopilus sapine us and Agrocybe praecox converted top quantities of PAH in the absence of p eroxidases, manganese peroxidases, and lignin peroxidases. The relative con tributions of intra- and extracellular enzymes to the conversion of PAH and the possible role of the fungi in the long-term detoxification of soil xen obiotics are discussed.