Study of mixed function oxidase system in Aspergillus ochraceus (NCIM 1146)

Abstract

Aspergillus ochraceus (NCIM-1146) has shown the ability to degrade cholesterol, camphor and naphthalene, when 96 h grown mycelium incubated in medium containing these organic compounds. Presence of higher level of electron transport components and biotransformation enzyme activity were observed in Aspergillus ochraceus, when grown in potato dextrose medium for 96 h. The enzyme activity preferred NADPH as a cofactor and shows inhibition in the presence of CO, indicating cytochrome P-450 mediated reactions. A signifi cant increase in the levels of electron transport components and biotransformation enzyme activity were observed in presence of different inducers (viz. cholesterol, camphor, naphthalene, veratrole, phenobarbital, n-hexane, kerosene and saffola oil) when compared with mycelium incubated in same way with similar conditions for 2 min incubation. Analyses of the products of cholesterol and camphor using HPLC and GCMS confi rm the degradation of these compounds.

Screening of Filamentous Fungi to Identify Biocatalysts for Lupeol Biotransformation

“…This structural modification can be supported by the intensity of the fragment ion m/z 147 in the MS spectrum of compound 2 , which is higher than in the MS spectrum of compounds 3 , 4 , 5 and lupeol (see Figure 2 ). Eliminations of alkyl groups and other size chain have been previously reported to be promoted by this fungus [ 35 ]. Otherwise, the molecular ion of compound 3 ( m/z 424) is two mass units lower than that of lupeol ( m/z 426), which can be associated with the formation of a double bond.…”

Improved 11α-hydroxycanrenone production by modification of cytochrome P450 monooxygenase gene in Aspergillus ochraceus

“…This enzyme introduces oxygen atoms at specific sites in the steroid backbone to convert lipophilic steroidal compounds into relatively hydrophilic derivatives (18). Cytochrome C reductase (CPR) and hexane oxidase are mediated by CYP in Aspergillus ochraceus, and these CYP-linked monooxygenases can be used to catalyse the conversion of cycloxanthone into 11α-hydroxyxanthone (19,20). However, the biocatalytic specificities of A. ochraceus vary for different steroid substrates, and its catalytic efficiency is low.…”