Lipid production from biodiesel-derived crude glycerol by Rhodosporidium fluviale DMKU-RK253 using temperature shift with high cell density

Abstract

Lipid production from crude glycerol by Rhodosporidium fluviale DMKU-RK253 was optimized using response surface methodology (RSM). The optimal medium (100mL in 500mL Erlenmeyer flask) consisting of 70g/L crude glycerol, 0.55g/L (NH4)2SO4, 1g/L monosodium glutamate, 2g/L MgSO4·7H2O, 0.4g/L KH2PO4 (C/N ratio of 140) and optimal cultivation conditions, namely pH 5.5, 25°C and 200rpm shaking speed (129h−1 of kLa) were obtained. Batch cultivation in a 5L jar fermenter performed with the optimal nutrients and conditions resulted in a high lipid content of 63.8% of dry biomass with a lipid quantity of 8.99g/L and a lipid yield of 0.16g/g. To enhance lipid production, a two-stage cultivation process with three different strategies viz. nutrient and temperature shift cultivation, temperature shift cultivation and temperature shift cultivation with high cell density was performed. The temperature shift cultivation (30°C to 25°C) with the high cell density strategy provided a high lipid quantity of 15.98g/L, a biomass of 22.93g/L (69.5% lipid content and lipid yield of 0.21g/g) and small amount of lipid droplets were observed in the cultivation medium.