Metabolism of fatty acid in yeast: addition of reducing agents to the reaction medium influences β-oxidation activities, γ-decalactone production, and cell ultrastructure in Sporidiobolus ruinenii cultivated on ricinoleic acid methyl ester

• Published in: Canadian journal of microbiology Vol. 53; no. 6; pp. 738 - 749
• Main Authors: Feron, G, Mauvais, G, Lherminier, J, Michel, J, Wang, X.D, Viel, C, Cachon, R
• Format: Journal Article
• Language: English
• Published: Ottawa, ON National Research Council of Canada 01.06.2007; NRC Research Press
• Subjects: Basidiomycota; Basidiomycota - drug effects; Basidiomycota - metabolism; Basidiomycota - ultrastructure; beta-oxidation; Biological and medical sciences; biosynthesis; Chemical properties; Culture Media - chemistry; Culture Media - pharmacology; dithiothreitol; Esters; fatty acid esters; Fatty acid metabolism; Fatty Acids - metabolism; Fundamental and applied biological sciences. Psychology; gamma-decalactone; hydrogen; hydrogène; Influence; lactones; Lactones - metabolism; Life Sciences; lipid metabolism; Microbiology; Microbiology and Parasitology; Microscopy, Electron, Transmission; Models, Chemical; Molecular Structure; NAD; odor compounds; oxidation; Oxidation-Reduction - drug effects; oxidoreduction potential; potentiel d'oxydo-réduction; redox potential; reducing agents; Reducing agents (Chemistry); Reducing Agents - pharmacology; ricinoleic acid; ricinoleic acid methyl ester; Ricinoleic Acids - chemistry; Ricinoleic Acids - metabolism; Sporidiobolus; Sporidiobolus ruinenii; Yeast fungi; yeasts; β-oxidation; β-oxydation; γ-decalactone; Canada; Fungi; Yeast; Sporidiobolus; Ultrastructure; β Oxidation; Lipids; Metabolism; Fatty acids; Basidiomycota; BETA-OXIDATION; NAD; HYDROGEN; EH; SPORIDIOBOLUS; DITHIOTHREITOL; OXIREDUCTION POTENTIAL; GAMMA-DECALACTONE
• ISSN: 0008-4166; 1480-3275
• DOI: 10.1139/W07-028

The sensitivity of Sporidiobolus ruinenii yeast to the use of reducing agents, reflected in changes in the oxidoreduction potential at pH 7 (Eh 7 ) environment, ricinoleic acid methyl ester catabolism, γ-decalactone synthesis, cofactor level, β-oxidation activity, and ultrastructure of the cell, was studied. Three environmental conditions (corresponding to oxidative, neutral, and reducing conditions) were fixed with the use of air or air and reducing agents (hydrogen and dithiothreitol). Lowering Eh 7 to neutral conditions (Eh 7 = +30 mV and +2.5 mV) favoured the production of lactone more than the more oxidative condition (Eh 7 = +350 mV). In contrast, when a reducing condition was used (Eh 7 = -130 mV), the production of γ-decalactone was very low. These results were linked to changes in the cofactor ratio during lactone production, to the β-oxidation activity involved in decanolide synthesis, and to ultrastructural modification of the cell.