Fungal metabolism of biphenyl

Cunninghamella elegans grown on Sabouraud dextrose broth transformed biphenyl to produce 2-, 3- and 4-hydroxybiphenyl, as well as 4,4'-dihydroxybiphenyl as free phenols. A compound tentatively identified as 2,4'-dihydroxybiphenyl was also produced. When 4-hydroxybiphenyl or 2-hydroxybiphenyl replaced biphenyl as the substrate, C. elegans produced 4,4'-dihydroxybiphenyl and 2,5-dihydroxybiphenyl respectively. The compound identified as 2,4'-dihydroxybiphenyl was produced from both substrates. A survey of 11 species of fungi known to degrade hydrocarbons revealed two species that were comparable to C. elegans in their ability to convert biphenyl into free phenols. In addition to free phenolic metabolites, deconjugation experiments indicated that 44% of the known metabolites present in the culture filtrate were present in the form of conjugates. These results suggest that the transformation of biphenyl by C. elegans is similar to that found in mammalian systems.