Production of biolipid, protein, and carotenoid by R. glutinis As2.703 utilizing a multiple-carbon source system

The utilization of renewable resources, such as agricultural waste, for the production of energy and chemicals represents a significant way for the resolution of the energy crisis and the mitigation of environmental concerns. In this study, corncob was used as a raw material for the production of biolipid, protein and carotenoid by fermentation of R. glutinis As2.703. Biolipid can further converted into biodiesel, while protein and carotenoid can be used as feed additives. The effects of different substrates, including glucose, xylose, acetic acid, glycerol, and different types of corncob hydrolysate on the growth and fermentation of R. glutinis As2.703 were investigated to elucidate the production patterns of lipid, protein, and carotenoid under multiple substrates. The results revealed that the carbon metabolism pattern of R. glutinis As2.703 in the presence of multiple substrates was that glucose and acetic acid were consumed first, followed by xylose and glycerol. Using a mixed hydrolysate of cellulose and hemicellulose containing glycerol as the substrate, 77.44 g of lipid, 40.76 g of protein, and 20.74 mg of carotenoid can be obtained from 1 kg of corncob and the high-lipid yield route is suitable for biodiesel production. When the glycerol-free mixed cellulose and hemicellulose hydrolysate was used as the substrate, 31.49 g of lipid, 74.77 g of protein, and 62.98 mg of carotenoid can be obtained from 1 kg of corncob. This high-protein content, coupled with a lipid and carotenoid composition, gives it the potential to be used as a feed additive, and direct utilization of whole cells reduces the cost of isolation and makes it a more economical route.