(546a) Studying Inhibitory Effects of Lignocellulosic Hydrolysate on Fungal Lipid Accumulation

Microbial 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 to tailor lignocellulose processing for enhanced lipid fermentation. The novel co- and combined hydrolysis process we developed could remove steps of detoxification, liquid-solid separation and washing as well as improve the efficiency of chemical usage during bioprocessing of lignocellulose. The oleaginous fungus M. isabellina cell mass and lipid fermentation on hydrolysate was compared with that from synthetic ones, indicating the integration of co- and combined-hydrolysis with oleaginous fungal lipid fermentation is a technically feasible way to lignocellulose-based biodiesel production. However, the inhibitors present in thermal-chemically pretreated hydrolysates showed negative effect on the growth and lipid formation of microorganisms. Understanding their inhibitory mechanism on oleaginous microorganism could help improving the efficiency of lignocellulose hydrolysis and lipid fermentation. Four lignocellulosic byproducts in lignocellulosic hydrolysates, including furfural, HMF, ferulic acid and coumaric acid were systematically investigated to elucidate their effects on the cell growth and lipid accumulation of M. isabellina. The results showed that their inhibitory effect on cell growth was more serious than on the lipid synthesis.