Characterisation of coupling products formed by biotransformation of biphenyl and diphenyl ether by the white rot fungus Pycnoporus cinnabarinus

Abstract

Cells of the white rot fungus Pycnoporus cinnabarinus grown in glucose were able to hydroxylate biphenyl and diphenyl ether, although growth was inhibited by these substrates at concentrations above 250 microM. 2- and 4-Hydroxybiphenyl were detected as products of biphenyl metabolism and 2- and 4-hydroxydiphenyl ether as products of diphenyl ether metabolism in the culture media. After addition of 2-hydroxydiphenyl ether and 2-hydroxybiphenyl to cell-free supernatants containing laccase as the only ligninolytic enzyme, different coloured precipitates were formed. HPLC analysis revealed the formation of additional hydrophobic metabolites with one major product per transformation. Mass spectrometric analysis of the methyl derivatives of the polymer mixture indicated dimers and trimers with different binding types. The main products were identified as dimers with carbon-carbon bonds in para-position to the hydroxyl group of the monomers by mass spectroscopy and nuclear magnetic resonance spectroscopy.

Laccase Functionalization of Flax and Coconut Fibers

“…Laccase oxidative coupling reactions involving different types of soluble molecules to lignin or lignin model substrates has previously been described for wood based materials [16,21]. In our previous mechanistic studies, the use of defined model substrates revealed that both 5-5 and 4-O-5 coupling reactions were possible [16,[21][22][23] and this can be used to explain the couplings in this study.…”

Biodiversity of Dioxin-Degrading Microorganisms and Potential Utilization in Bioremediation.

“…However, the involvement of laccase should be assumed because of its presence in many fungal taxa capable of degrading similar aromatic structures. Laccase of the white rot fungi, Trametes versicolor and Pycnoporus cinnabarinus, was shown to transform 2-hyxroxyDF 96) . P. cinnabarinus laccase was reported to be capable of dehalogenating chlori-nated hydroxybiphenyls 167) .…”

Improvement of the Antifungal Activity Against Botrytis Cinerea of Syringic Acid, a Phenolic Acid From Grape Pomace

“…Also, dimerization, oligomerization, and polymerization of phenolic compounds can be obtained 8 . This enzyme has been used to synthesize hydroxybiphenyl dimers 14 , isoeugenol dimers 15 , and ferulic acid dimers 16 . Laccase is also able to couple a laccase substrate with a non-laccase substrate (known as a mediator) to create new molecules (heterodimers) 8,17 .…”