Separation of xylose and glucose using an integrated membrane system for enzymatic cofactor regeneration and downstream purification

Broad substrate specificity of glucose dehydrogenase (EC (GDH) lead to partial conversion of xylose to xylonic acid, causing some loss of xylose, but the results obtained nevertheless showed that it is possible to build a robust system for conducting enzyme reactions by sequentially regenerating the cofactor and at the same time obtaining valuable products of high purity. Read more

Significance of membrane bioreactor design on the biocatalytic performance of glucose oxidase and catalase: Free vs. immobilized enzyme systems.

Membrane separation of xylose and glucose can be accomplished via oxidation of glucose to gluconic acid by enzymatic glucose oxidase catalysis. Oxygen for this reaction can be supplied via decomposition of hydrogen peroxide by enzymatic catalase catalysis. In order to maximize the biocatalytic productivity of glucose oxidase and catalase (gluconic acid yield per total amount of enzyme) the following system set-ups were compared: immobilization of glucose oxidase alone; co-immobilization of glucose oxidase and catalase; glucose oxidase and catalase free in the membrane bioreactor. Read more

Biomass-Water Interactions Correlate to Recalcitrance and Are Intensified by Pretreatment: An Investigation of Water Constraint and Retention in Pretreated Spruce Using Low Field NMR and Water Retention Value Techniques.

This study investigates the correlation between biomass recalcitrance and the constraint and retention of water by the biomass, using SO2 pretreated spruce, a common feedstock for lignocellulosic biofuel production, as a substrate to evaluate this relationship. The water retention value (WRV) of the pretreated materials was measured, and water constraint was assessed using time domain Low Field Nuclear Magnetic Resonance (LFNMR) relaxometry. WRV increased with pretreatment severity, correlating to reduced recalcitrance, as measured by hydrolysis of cellulose using commercial enzyme preparations. Water constraint increased with pretreatment severity, suggesting that a higher level of biomass-water interaction is indicative of reduced recalcitrance in pretreated materials. Both WRV and water constraint increased significantly with reductions in particle size when pretreated materials were further milled, suggesting that particle size plays an important role in biomass water interactions. It is suggested that WRV may be a simple and effective method for measuring and comparing biomass recalcitrance. Read more