Effects of changes in the major carbon source on the fatty acids of Euglena gracilis.

Abstract

AbstractEuglena gracilis was cultured under both heterotrophic and phototrophic growth conditions using ethanol, glucose or CO2 as the major carbon source. Total fatty acid analyses indicated that ethanol produced more highly unsaturated acids than did glucose under both growth conditions. Growth in the light on CO2 yielded a very high content of 18∶3, 16∶3 and 16∶4 (33%), compared to ethanol (11%) or glucose (10%). These two preformed carbon sources enhanced the content of the C20 and C22 polyenes compared to CO2, and growth in the dark on to CO2, and growth in the dark on ethanol caused a further increase in these polyenes. Growth in the dark on glucose caused only a slight increase of the C20 and C22 polyenes compared to growth in the light on this carbon source. When the fatty acid patterns of the two dark‐grown heterotrophs were compared, two observations were quite evident. First, there was a two‐fold increase in the saturated acids in the cells grown on glucose. This was largely due to myristic acid. Second, the C20 and C22 polyenes were almost twice as concentrated in the cells grown on ethanol.