U37K′ values for Isochrysis galbana as a function of culture temperature, light intensity and nutrient concentrations

The alkenone producing species Isochrysis galbana has been cultured at different temperatures, nutrient and light levels, to investigate effects of genetic and environmental variation on U37K′. The experiments show that: (1) the U37K′–temperature relationship of I. galbana differs significantly from such relationships established for other species, (2) U37K′ values are not significantly influenced by nitrogen limitation, (3) U37K′ values are influenced by phosphate and light limitation equivalent to temperature decreases of about 5–7°C at 16°C. Temperature thus is not the only variable capable of changing alkenone unsaturation and the model that alkenones play a role in membrane fluidity regulation alone, seems too simple.