1887

Abstract

, a fungus used commercially as a source of arachidonic acid, 20:4(-6), has been examined to see if growth on lipid-based carbon sources leads to repression of either fatty acid biosynthesis and/or fatty acid desaturation and elongation. Changes in the activities of ATP:citrate lyase, isocitrate lyase, carnitine acetyltransferase, malic enzyme, glucose-6-phosphate dehydrogenase and pyruvate kinase when the fungus was grown on fatty-acid-based (Tween) carbon sources were consistent with (i) the cells using the fatty acyl portion of the substrate as the sole carbon source, (ii) pyruvate kinase being the source of pyruvate for biosynthesis under these conditions and (iii) malic enzyme’s major function being as a provider of NADPH for lipid biosynthesis. The abolition of fatty acid synthase activity when cells were grown on Tweens indicated the cessation of fatty acid biosynthesis under these conditions. The fatty acyl composition of the lipid accumulated by the fungus grown on Tweens 20, 40 and 80 showed that desaturation and elongation of the substrate lipid still occurred. The absolute amount of arachidonic acid synthesized by Tween-grown cells was the same as for cells grown on glucose. The transformation of incorporated fatty acids into 20:4(-6) was, it appeared, limited at the elongation of 18:3(-6) to 20:3(-6) as, in every case, 18:1, 18:2 and 18:3(-6) increased in amount in the Tween-grown cells. These data show for the first time that fatty acid synthesis is regulated separately from fatty acid desaturation/elongation and that the latter reactions are not repressed by growth of the fungus on simple fatty acids. Furthermore, the data strongly implicate the elongation of 18:3(-6) to 20:3(-6) as the limiting step in arachidonic acid biosynthesis by .

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2000-09-01
2024-04-24
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References

  1. Armitt S., McCullough W., Roberts C. F. 1976; Analysis of acetate non-utilizing mutants in Aspergillus nidulans. J Gen Microbiol 92:263–282 [CrossRef]
    [Google Scholar]
  2. Boulton C. A., Ratledge C. 1983; Partial purification and some properties of ATP:citrate lyase from the oleaginous yeast Lipomyces starkeyi. J Gen Microbiol 129:2863–2869
    [Google Scholar]
  3. Butte W. 1983; Rapid method for the determination of fatty acid profiles from fats and oils using trimethylsulphonium hydroxide for transesterification. J Chromatogr 261:142–145 [CrossRef]
    [Google Scholar]
  4. Certik M., Balteszova L., Sajbidor J. 1997; Lipid formation and γ-linolenic acid production by Mucorales fungi grown on sunflower oil. Lett Appl Microbiol 25:101–105 [CrossRef]
    [Google Scholar]
  5. Dittrich F., Zajonc D., H ü hne K.8 other authors 1998; Fatty acid elongation in yeast: biochemical characteristics of the enzyme system and isolation of elongation-defective mutants. Eur J Biochem 252:477–485 [CrossRef]
    [Google Scholar]
  6. Folch J., Less M., Sloane-Stanley G. H. 1957; A simple method for the isolation and purification of total lipides from animal tissues. J Biol Chem 226:497–509
    [Google Scholar]
  7. Gill I., Valivety R. 1997; Polyunsaturated fatty acids, part 1: occurrence, biological activities and applications. Trends Biotechnol 15:401–409 [CrossRef]
    [Google Scholar]
  8. Holdsworth J. E., Veenhuis M., Ratledge C. 1988; Enzyme activities in oleaginous yeasts accumulating and utilizing exogenous or endogenous lipids. J Gen Microbiol 134:2907–2915
    [Google Scholar]
  9. Kawamoto S., Ueda M., Nozaki C., Yamamura M., Tanaka A., Fukui S. 1978; Localization of carnitine acetyltransferase in peroxisomes and in mitochondria of n-alkane grown Candida tropicalis. FEBS Lett 96:37–40 [CrossRef]
    [Google Scholar]
  10. Kendrick A., Ratledge C. 1992; Desaturation of polyunsaturated fatty acids in Mucor circinelloides and the involvement of the novel membrane-bound malic enzyme. Eur J Biochem 209:667–673 [CrossRef]
    [Google Scholar]
  11. Kendrick A., Ratledge C. 1996; Cessation of polyunsaturated fatty acid formation in four selected filamentous fungi when grown on plant oils. J Am Oil Chem Soc 73:431–435 [CrossRef]
    [Google Scholar]
  12. Kohlaw G. B., Tan-Wilson A. 1977; Carnitine acetyltransferase: candidate for the transfer of acetyl groups through the mitochondrial membrane of yeast. J Bacteriol 129:1159–1161
    [Google Scholar]
  13. Kyle D. J. 1997; Production and use of a single cell oil highly enriched in arachidonic acid. Lipid Technol 9:116–121
    [Google Scholar]
  14. McCullough W., Roberts C. F. 1974; The role of malic enzyme in Aspergillus nidulans. FEBS Lett 41:238–242 [CrossRef]
    [Google Scholar]
  15. Ratledge C. 1992; Microbial lipids: commercial realities or academic curiosities. In Industrial Applications of Single Cell Oils pp. 1–15Edited by Kyle D., Ratledge C. Champaign: AOCS Press;
    [Google Scholar]
  16. Ratledge C. 1997; Microbial lipids. In Biotechnology vol. 7Products of Secondary Metabolism pp. 135–197Edited by Kleinkauf H., von Dohren H. Weinheim: VCH;
    [Google Scholar]
  17. Rodriguez-Ruiz J., Belarbi E., Sanchez J. L. G., Alonso D. L. 1998; Rapid simultaneous lipids extraction and transesterification for fatty acid analyses. Biotechnol Tech 12:689–691 [CrossRef]
    [Google Scholar]
  18. Schwitzguébel J. P., Møller I. M., Palmer J. M. 1981; Changes in density of mitochondria and glyoxysomes from Neurospora crassa: a re-evaluation utilizing silica sol gradient centrifugation. J Gen Microbiol 126:289–295
    [Google Scholar]
  19. Shimizu S., Kawashima H., Akimoto K., Shinmen Y., Yamada H. 1989a; Conversion of linseed oil to a eicosapentaenoic acid-containing oil by Mortierella alpina IS-4 at low temperature. Appl Microbiol Biotechnol 32:1–4
    [Google Scholar]
  20. Shimizu S., Kawashima H., Akimoto K., Shinmen Y., Yamada H. 1989b; Microbial conversion of an oil containing α-linolenic acid to an oil rich in eicosapentaenoic acid. J Am Oil Chem Soc 66:342–347 [CrossRef]
    [Google Scholar]
  21. Shinmen Y., Kawashima H., Shinmen S., Yamada H. 1992; Concentration of eicosapentaenoic acid and docosapentaenoic acid in an arachidonic acid-producing fungus, Mortierella alpina IS-4, grown with fish oil. Appl Microbiol Biotechnol 38:301–304
    [Google Scholar]
  22. Worthington Enzymes 1979; Pyruvate kinase. In Enzymes and Related Biochemicals pp. 179–180 Bedford, MA: Millipore;
    [Google Scholar]
  23. Wynn J. P. 1994 Intermediary metabolism of Fusarium moniliforme PhD thesis University of Hull;
    [Google Scholar]
  24. Wynn J. P., Ratledge C. 1997; Malic enzyme is a major source of NADPH for lipid accumulation in Aspergillus nidulans. Microbiology 143:253–257 [CrossRef]
    [Google Scholar]
  25. Wynn J. P., Kendrick A., Ratledge C. 1997; Sesamol as an inhibitor of growth and lipid metabolism in Mucor circinelloides via its action on malic enzyme. Lipids 32:605–610 [CrossRef]
    [Google Scholar]
  26. Wynn J. P., Hamid A. A., Midgley M., Ratledge C. 1998; Widespread occurrence of ATP:citrate lyase and carnitine acetyltransferase in filamentous fungi. World J Microbiol Biotechnol 14:145–147
    [Google Scholar]
  27. Wynn J. P., Hamid A. A., Ratledge C. 1999; The role of malic enzyme in the regulation of lipid accumulation in filamentous fungi. Microbiology 145:1911–1917 [CrossRef]
    [Google Scholar]
  28. Zink M. W. 1972; Regulation of the two ‘malic’ enzymes in Neurospora crassa. Can J Microbiol 18:611–617 [CrossRef]
    [Google Scholar]
  29. Zink M. W., Katz J. S. 1973; Malic enzyme of Fusarium oxysporum. Can J Microbiol 19:1187–1196 [CrossRef]
    [Google Scholar]
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