Effects of dilution rate and carbon-to-nitrogen ratio on lipid accumulation by Rhodosporidium toruloides under chemostat conditions

Abstract:

The objective of this work is to investigate how dilution rate and carbon-to-nitrogen (C/N) ratio affects lipid accumulation by Rhodosporidium toruloides AS 2.138 9 in continuous culture. Under steady-state conditions, the increase in dilution rate led to the decrease in lipid content and lipid yield. The highest lipid yield and lipid content at D=0.02 h?1 were 0.18 g lipid/g sugar and 57.1%, respectively, while the highest lipid productivity and biomass productivity were obtained at D=0.14 h?1. The increase in C/N ratio led to the increase in lipid content. The highest lipid content of 38% was obtained at C/N=237. The highest lipid yield of 0.12 g lipid/g sugar was obtained at C/N=92. However, the highest lipid productivity of 0.12 g/(L·h) was obtained at C/N=32. No significant changes were observed in terms of fatty acid composition of the lipid produced under different C/N ratios, and these three fatty acids, palmitic acid, stearic acid and oleic acid, took over 85% in all samples.

Key words:Rhodosporidium toruloides, chemostat, dilution rate, carbon-to-nitrogen ratio, lipid