Fluorene oxidation in vivo by Phanerochaete chrysosporium and in vitro during manganese peroxidase-dependent lipid peroxidation

• Published in: Applied and Environmental Microbiology 1996-05, Vol.62 (5), p.1788-1792
• Main Authors: BOGAN, B. W, LAMAR, R. T, HAMMEL, K. E
• Format: Article
• Language: English
• Subjects: aromatic hydrocarbons; biodegradacion; biodegradation; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Cellular biology; Enzymes; Fundamental and applied biological sciences. Psychology; Fungi; hidrocarburos; hidrocarburos aromaticos; Hydrocarbons; hydrocarbure; hydrocarbure aromatique; lipid peroxidation; manganese; manganeso; metabolism; metabolisme; metabolismo; Mission oriented research; oxidacion; Oxidation; oxydation; peroxidacion lipidica; peroxidasas; peroxidases; peroxydase; peroxydation des lipides; Phanerochaete chrysosporium; Physiology and metabolism
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.62.5.1788-1792.1996

The oxidation of fluorene, a polycyclic hydrocarbon which is not a substrate for fungal lignin peroxidase, was studied in liquid cultures of Phanerochaete chrysosporium and in vitro with P. chrysosporium extracellular enzymes. Intact fungal cultures metabolized fluorene to 9-hydroxyfluorene via 9-fluorenone. Some conversion to more-polar products was also observed. Oxidation of fluorene to 9-fluorenone was also obtained in vitro in a system that contained manganese(II), unsaturated fatty acid, and either crude P. chrysosporium peroxidases or purified recombinant manganese peroxidase. The oxidation of fluorene in vitro was inhibited by the free-radical scavenger butylated hydroxytoluene but not by the lignin peroxidase inhibitor NaVO3. Manganese(III)-malonic acid complexes could not oxidize fluorene. These results indicate that fluorene oxidation in vitro was a consequence of lipid peroxidation mediated by P. chrysosporium manganese peroxidase. The rates of fluorene and diphenylmethane disappearance in vitro were significantly faster than those of true polycyclic aromatic hydrocarbons or fluoranthenes, whose rates of disappearance were ionization potential dependent. This result indicates that the initial oxidation of fluorene proceeds by mechanisms other than electron abstraction and that benzylic hydrogen abstraction is probably the route for oxidation.