Kinetics of continuous cultivation of the oleaginous yeast Rhodosporidium toruloides

• Continuous cultivation of Rhodosporidium toruloides under carbon limitation.
• Continuous cultivation of Rhodosporidium toruloides under nitrogen limitation.
• Culture process parameters determined.
• Established relationship between specific lipid production rate and dilution rate.

Microbial lipids are potential alternative feedstock for biofuel and oleochemical industries. The oleaginous yeast Rhodosporidium toruloides AS 2.1389 is an excellent lipid producer. To attain parameters for the understanding of the lipid production process, we performed continuous cultivation experiments under either carbon or nitrogen limitation. The maintenance coefficient and maximum cell mass yield for this yeast were determined as 5.7 mg glucose/g cell/h and 0.42 g cell/g glucose, respectively, under carbon limitation. Under nitrogen limitation, the highest lipid yield of 0.19 g/g was observed at the dilution rate of 0.02 h−1 while the highest specific lipid formation rate of 0.058 g/g cell/h at the dilution rate of 0.08 h−1. A kinetic model of lipid formation under steady state conditions was developed, parameters estimated, and optimal continuous cultivation conditions forecasted. These data should be very helpful to develop and design more efficient bioprocesses for microbial lipid production.