Enhanced simultaneous saccharification and fermentation process for cellulosic lipid production by Cryptococcus curvatus

This presentation reports the application of simultaneous saccharification and fermentation (SSF) for microbial lipid production using lignocellulose by oleaginous yeast Cryptococcus curvatus. In order to enhance the lipid production, we firstly explored the capability of utilizing mixed sugars existing in the SSF hydrolysate. We found that xylose and cellobiose could be simultaneously consumed at similar rates. The total sugar consumption rates kept constant regardless of the sugar composition in the mixtures, and the cell biomass and lipid production cultured on the different sugar mixtures were comparable to those on glucose. Taking advantages of this effective xylose/cellobiose co-fermentation approach, we further developed an efficient SSF process with unique enzyme addition strategy to achieve simultaneous fermentation of glucan and xylan from lignocellulose. Compared to xylose accumulation with extra β-glucosidase (BGL) supplementation, simultaneous consumption of xylose and cellobiose was observed in the absence of extra BGL. The results showed that without extra BGL addition C. curvatus reached the highest lipid concentration in a shorter time than those in the presence of BGL as well as in the absence of extra BGL lower hemicellulase loadings were required. This work provided a novel solution to significantly improve the economics of the application of SSF process for cellulosic lipid production.