Presence and Physiologic Regulation of Alcohol Oxidase Activity in an Indigenous Fungus Isolated from Petroleum-Contaminated Soils

Abstract

A soluble alcohol oxidase (AO) activity was detected in the mycelium of a filamentous fungus strain named YR-1, isolated from petroleum-contaminated soils. AO activity from aerobically grown mycelium was detected in growth media containing the hydrocarbons decane or hexadecane; the enzyme activity exhibited optimum pH for the oxidation of different alcohols (methanol, ethanol, and hexadecanol) similar to that of the corresponding aldehyde. Zymogram analysis conducted with purified fractions from aerobic mycelium of YR-1 strain extracts indicated the existence of two AO enzymes (AO-1 and AO-2). Purified samples of both enzymes analyzed by sodium dodecylsulf ate-polyacrylamide gel electrophoresis indicated the presence of three protein bands with molecular sizes 20, 38, and 46 kDa that could be part of the native enzyme. In samples of both enzymes, the 46-kDa protein gave a positive reaction in immunodetection experiments with antibodies directed against AO from Hansenula polymorphs The purified AO-2 enzyme oxidized different alcohols, although higher activity was displayed with hexadecanol. K m values obtained for methanol and hexadecanol indicated a higher affinity for the latter. Analysis of the aminoterminal sequence of the 46-kDa protein of AO-2 enzyme indicated significant similarity to enzymes involved in the metabolism of biphenyl polychloride compounds.Index EntriesAlcohol oxidasefilamentous fungihydrocarbon biodegradationPetroleum comtamination