Development and optimization of single and combined detoxification processes to improve the fermentability of lignocellulose hydrolyzates

In this work, an enzyme catalyzed detoxification process of lignocellulose hydrolyzates with immobilized laccase from Trametes versicolor was developed and optimized. Further, the immobilized laccase significantly reduced the amount of toxic phenolic compounds in the xylan rich fraction (XRF) by polymerization within 1 h. The insoluble products precipitated onto the carrier surface and could be reversible resolubilized by an aqueous ethanol solution. Consequently, an in situ product removal could be realized. The reusability of the immobilized laccase could be additionally shown. The reaction kinetics could be described by a reversible Michaelis Menten equation giving the prerequisite for scaling up the process. In a second step, the organic acids, hydroxymethylfurfural and phenolic acids could be further removed by employing an anion exchanger. Both, the laccase and the laccase + anion exchanger treatment enhanced successfully the fermentability of an organosolv wheat straw fraction.