Simon R. Fox1,2,3, Arzu Akpinar1,4, Asmita Prabhune1, J. Friend1, Colin Ratledge1
1Department of Biological Sciences, University of Hull, Hull, HU6 7RX, UK
2Department of Biotechnology The National Chemical Laboratory Pune 4110088 India
3Department of Brassica and Oilseeds Research John Innes Centre Norwich Research Park Norwich NR4 7UH UK
4Department of Food Engineering The University of Uludag Bursa Turkey
Tóm tắt
AbstractWhen the sewage fungus Leptomitus lacteus was grown in liquid culture aerobically and then transferred to medium containing long‐chain fatty acids, it produced a number of oxygenated fatty acids. From linoleic acid (18∶2n−6), the major metabolite produced was R‐8‐hydroxy‐9Z,12Z‐octadecadienoic acid (8R‐HODE), with additional quantities of 8,11‐di‐HODE, 11,16‐di‐HODE, and 11,17‐di‐HODE. Other fatty acid derivatives identified included 7‐HODE, 10‐HODE, and 13‐hydroxy‐octadecamonoenoic acid. Arachidonic acid (20∶4n−6) was metabolized primarily to 18‐ and and 19‐hydroxy‐eicosatetraenoic acids (18‐ and 19‐HETE) also as R enantiomers, along with smaller quantities of 17‐HETE, 9‐HETE, 14,15‐dihydroxyeicosatrienoic acid and 11,12,19‐trihydroxy‐eicosatrienoic acid. The oxygenated products of long‐chain fatty acids, in particular the biosynthesis of 8R‐HODE, a compound classified as a precocious sporulation inducer, were similar to those produced by an unrelated fungal species in the Ascomycota, the take‐all fungus Gaeumannomyces graminis. As in G. graminis, the biotransformation of linoleate to 8R‐HODE was not significantly inhibited by exposure of the organism to CO. This indicated that the enzyme responsible for 8R‐HODE biosynthesis in Leptomitus could be similar to that of G. graminis; yet we did not detect 7,8‐di‐HODE as a product of 18∶2n−6 metabolism as in G. graminis. CO did inhibit the biosynthesis of 14,15‐di‐HETE, 18‐HETE, and 19‐HETE in L. lacteus, which suggested the involvement of a cytochrome P450‐type monooxygenase. The biosynthesis of 8R‐HODE from 18∶2n−6 was found to occur in certain cell lysates, specifically in low speed (15,000×g) supernatant, following cell disruption.
