Waxmonoester fermentation in Euglena gracilis T. Factors favouring the synthesis of odd-numbered fatty acids and alcohols.
Waxmonoester fermentation at the expense of endogenous paramylon was followed in the dark in autotrophically grown Euglena gracilis. With reduced oxygen tension and decreasing O2-consumption rates the proportion of odd-numbered fatty acids and alcohols increased up to a molar ratio of nearly 1:1 under strictly anaerobic conditions. Labelled (14)CO2, succinate and propionate were incorporated into odd-numbered fatty acids and alcohols 11 to 33 times faster than in even-numbered chains. The electron-flow inhibitor rotenone diminished waxester formation in total, but especially CO2 fixation and the synthesis of odd-numbered chains, without impeding anaerobic carbohydrate breakdown. These findings are indicative for propionyl-CoA as an intermediate in the synthesis of odd-numbered chains. Its probable synthesis in the methylmalonyl-CoA pathway is discussed with regard to energetics.
Botanisches Institut der Universität, Kirschallee 1, D-5300, Bonn 1, Federal Republic of Germany.
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T
Schneider
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Betz