Pilot-scale conversion of corn stover into lipids by the red yeast Rhodosporidium toruloides

Microbial lipid-based biorefinery has gained much attention because of its potential social and environmental benefits. While several studies were done on lipid production from lignocellulosic biomass at small scale, many processing details were not well-documented, and the suitability for scaling-up remained unclear. Here we report results of lipid production from corn stover (CS) by the red yeast Rhodosporidium toruloides CGMCC 2.1389 in a 1000-L bioreactor. The entire process included alkaline pretreatment, enzymatic hydrolysis, hydrolysates preparation, cell cultivation, and lipid recovery. It was found that the hydrolysates preparation step was heavily affected by the performance of its preceding steps. We achieved CS digestibility up to 90% and successfully obtained hydrolysates for lipid production at a yield of 0.17 g lipid per g total reducing sugar. Enzyme-assisted lipid recovery from the culture broth was also verified at a 50-L scale with a total lipid extraction rate of 74%. Overall, the conversion of CS into microbial lipids was fully verified at pilot-scale, and key issues were identified for further improvements in future studies.