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Abstract
Lipid contents of yeasts grown on glucose were: Candida lipolytica, 5·4%; C. tropicalis, 9·4%; C. utilis, 2·7%; Candida 107, 41%; Hansenula anomala, 12·5%; Rhodotorula glutinis, 2·7%; and R. graminis, 9·1%. In each yeast about 80% of the lipid consisted of triglycerides. When the triglycerides from five of the yeasts were analysed in detail, an unsaturated acid was invariably found at the 2-position. With Candida 107 and R. graminis about 50% of the total triglyceride fatty acids were saturated, resulting in over 50% of the triglycerides being of the 1,3-disaturated-2-monounsaturated type. When Candida 107 and C. tropicalis were grown on individual n-alkanes, from C12 to C16, the fatty-acid composition varied according to the chain length of the substrate, although with n-tridecane neither yeast produced tridecanoic acid in the triglycerideand with n-dodecane only C. tropicalis contained an appreciable amount of dodecanoic acid in the triglyceride (32% of the fatty acids). With both yeasts on each alkane substrate, the lipid contents were not only lower than when grown on glucose but contained a smaller proportion of triglyceride. Saturated acids were now located at the 2-position of the triglycerides: Candida 107 grown on n-tetradecane produced 46% of its triglycerides with a saturated acid at the 2-position. The main advantage to be gained by growing yeasts on n-alkanes is, as far as lipid formation is concerned, the biosynthesis of specific fatty acids rather than the production of plant-like triglycerides.
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