Temperature shifts in regulation of lipids accumulated byLipomyces starkeyi

The effect of temperature on the accumulating triglycerides ofLipomyces starkeyi was studied in 10‐L fermentation experiments. The temperature during the growth, lipid accumulation and postaccumulation phases was altered. The cellular lipid content, the glucose conversion efficiency and the specific lipid production rate were highest when the growth phase temperature was 28°C, instead of 16–18°C. The temperature of the accumulation phase had an influence on the lipid quality at the end of the accumulation. Oleic acid content increased from 52 to over 60% when the accumulation phase temperature was decreased from 28 to 15°C and, concomitantly, palmitic acid decreased from 33 to 26%. The degree of fatty acid unsaturation was the highest (0.75 Δmol−1) when the accumulation phase temperature was the lowest (15°C) andvice versa. The temperature shift after the lipid accumulation phase affected neither the composition nor the amount of the accumulated lipids. In conclusion, the temperature profile for the highest lipid yield with the most desired composition should be: (i) a growth phase temperature that gives the maximum growth rate and (ii) an accumulation phase temperature that produces the desired ratio of palmitic to oleic acid.