Effects of culture condition and nutrition on the co-production of microbial oil and exopolysaccharide by Sporidiobolus pararoseus JD-2

Abstract

Microbial oil has been gaining considerable attention from researchers recently as renewable and ecofriendly oil and its potential as feedstock for food industry and biodiesel industry. In this context, we have earlier demonstrated production of microbial oil and exopolysaccharide (EPS) from the yeast Sporidiobolus pararoseus JD-2. In this study, we explored increasing its production by optimizing the culture condition and nutrition. As expected, culture temperature and dissolved oxygen (DO) are the contributing factors for co-producing microbial oil and EPS, in which 28℃ and lower quantum (i.e., 30 mL/500 mL) show the best conditions in shake-flasks fermentation. By contrast, the initial pH from 4 to 8 has no obvious effect on producing microbial oil and EPS. In addition, the culture nutrition (i.e., carbon/nitrogen source) were also discussed, and indicating that 20 g/L of corn steep liquor and 60 g/L of glucose are beneficial to produce microbial oil and EPS (i.e., 34.1±1.2 g/L and 11.5±0.2 g/L, respectively). Meanwhile, the residue glucose should be maintained at 20 g/L, in which the highest production of microbial oil and EPS was obtained (i.e., 34.6±1.7 g/L and 11.7±0.8 g/L, respectively). The biomass, microbial oil and EPS were further increased during optimizing the DO level, which reached to 67.8±2.1 g/L, 34.7±0.6 g/L and 11.8±0.5 g/L during maintaining DO level at 20-30%, respectively. The results suggest that appropriate culture condition and nutrition considerably improve the fermentation performance of S. pararoseus JD-2 and significantly increase co-production of microbial oil and EPS (by 11.2 and 8.3%, respectively) compared to the un-optimized fermentation.