Development of an advanced biological process to convert lignocellulose into lipid-based fuel

Fungal lipid accumulated from lignocellulose has received growing attention as a precursor for advanced biofuels and functional oils. Despite its promise, the full potential of lignocellulose has yet to be unlocked partly because of the major challenges associated with its bioconversion such as liquid-solid separation, large water usage, detoxification, and low xylan utilization. Therefore, it is critical to develop new methods in order to tailor lignocellulose processing for enhanced fungal lipid accumulation. A combined hydrolysis process, which first mixes dilute sulfuric acid and dilute sodium hydroxide pretreated corn stover at a 1:1 (w/w) ratio, followed directly by enzymatic saccharification, has been developed in this study in order to improve the efficiency of chemical uses, remove steps of neutralization, detoxification, liquid-solid separation and washing during the process of lignocellulosic biofuel production. The oleaginous fungus M. isabellina was selected and applied to the combined-hydrolysate as well as a synthetic hydrolysate to compare fungal lipid fermentation performance. Fungal cultivations on combined hydrolysate exhibited comparable cell mass and lipid yields with those from synthetic medium, indicating that the integration of combined-hydrolysis with oleaginous fungal lipid fermentation is a technically feasible way to improve efficiency of advanced lignocellulosic biofuel production. The key inhibitory compounds derived from the pretreatment of lignocellulosie corn stover were identified and their effect on cell growth and lipid production of oleaginous fungus M.isabellina was also investigated.