Production and Unsaturation Index of Alkenones During Batch and Continuous Cultures of the Coccolithophorid Alga, Emiliania Huxleyi

Abstract

Emiliania huxleyi (EH2 strain) was grown at 10, 15, 20 and 250C in batch and continuous cultures to assess the factors affecting the changes in the production and the unsaturation index of alkenones. The production of alkenones continued during growth and was greatly stimulated at IOOC where cell growth was greatly suppressed, but not influenced by the changing cell size. Alkenones are chemically and/or biologically stable compound for they can be detected even in broken or dead cells. The UK₃₇ and the ratio between C_36:2- ethyl alkenoate (EE) and total C₃₇ alkenones (K₃₇) (EE/K₃₇) changed during growing phase and remained nearly constant during the stationary phase at all temperatures tested in batch cultures. Data in continuous culture showed that the alkenones with 2 double bonds increased at high temperature. While the alkenones with 3 double bonds decreased and the reverse change was clearly observed when temperature was decreased. U^K' ₃₇ changed without any lag when temperature changed and needed approximately 2-6 days to attain the respective levels depending on the difference of temperature given. The final values of U^K' ₃₇ obtained at stationary stage were similar between batch and continuous cultures at each temperature and the values increased with increasing temperature. The results strengthened the suggestion that temperature is the major factor that influences the production and unsaturation of alkenones.