Co-fermentation of a sugar mixture for microbial lipid production in a two-stage fermentation mode under non-sterile conditions

The economical production of biodiesel from lignocellulose requires an effective co-fermentation of lignocellulose-derived sugars, such as glucose and xylose. Our present work discovered that Lipomyces starkeyi AS 2.1560 could produce microbial lipid effectively from co-fermentation of glucose and xylose in a two-stage culture mode under non-sterile conditions. High lipid production was achieved by a feed-batch fermentation process without sterility in the second fermentation stage. After incubation for 46 h in a bioreactor utilizing unsterile glucose and xylose solution, the cell biomass, lipid and lipid content reached 98.3 g L−1, 62.7 g L−1 and 63.8%, respectively. The results showed that the two-stage fermentation method should be a promising process to produce lipid from lignocellulose hydrolysates.