Metabolic engineering of Neurospora crassa for the production of xylitol and ethylene glycol from xylose

Abstract

The use of pentose from lignocellulose is critical for economic production of biofuels and chemicals. In this study, a filamentous fungus, Neurospora crassa, was used to metabolize xylose and synthesize xylitol and ethylene glycol (EG). Firstly, xylulose kinase gene was knocked out to prevent excessive xylose usage for strain growth, resulting in 5.8 ± 0.3 g/L xylitol and 58.3 ± 2.6 mg/L EG. Through optimization, the xylitol accumulation in the hydrolysate containing xylose reached 62.0 ± 0.6 g/L. The expression of 6-phosphofructokinase increased EG production with a maximum titer of 102.1 ± 1.8 mg/L, proving that the strain synthesized EG through xylulose-1-phosphate pathway. Addition of furfural or hydrolysate, and oxygen-limited environment were conducive to the EG accumulation. Further optimized strain accumulated EG up to 2586.4 ± 198.9 mg/L. This study provided the evidence of an all-natural metabolic pathway for EG synthesis in N. crassa and also demonstrated a new chassis cell for synthesis of xylitol and EG from xylose-rich hydrolysate.