Optimized delignification of wood‐derived lignocellulosics for improved enzymatic hydrolysis

Abstract

One of the major bottlenecks in the bioconversion of lignocelluosic feedstocks to liquid ethanol is the recalcitrance of residue following pretreatment, specifically softwood derived residues. Peroxide delignification has previously been shown to effectively aid in the removal of condensed lignaceous moieties from substrates following pretreatment, and thereby improve the hydrolyzability of the polymeric carbohydrates to their monomeric constituents. Despite the effectiveness of peroxide, drawbacks in this system still remain, as the concentration of peroxide required for adequate hydrolysis performance is currently uneconomical. In an attempt to improve the efficacy of the delignification process, we evaluated other post-treatment operations and concurrently attempted to limit the decomposition of peroxide loading; with the over arching aim to improve the efficiency of the bioconversion process. By employing several peroxide stabilizers and pre-chelating the steam exploded recalcitrant substrates, we were able to substantially improve the delignification treatment of Douglas-fir wood chips, and to reduce peroxide loading by more than 50% without negative effects on the hydrolysis rates and yield.

Effect of Different Pretreatment of Sugar Cane Bagasse on Cellulase and Xylanases Production by the MutantPenicillium echinulatum9A02S1 Grown in Submerged Culture

“…This reduction of crystallinity may be because H 2 O 2 pretreatment can swell and dissolve cellulose, while NaOH can even penetrate into the amorphous area of cellulose and destruct the neighboring crystalline regions [30] (Wang et al 2008). EDTA is used in the process to prevent the decomposition of peroxide [31]. The anthraquinone also has important function during the pretreatment, since it is agent which reduces lignin intermediates formed during pulping and thereby prevents the lignin intermediates from condensing during pulping [32].…”

Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls

“…In contrast, sugar yields were poorly related to the lignin content of CWDHP-controls and their alkali-insoluble residues ( P > 0.10). Removal of lignin (and possibly hemicelluloses) by alkali probably enhanced the exposure of structural polysaccharides to hydrolytic enzymes and reduced non-productive binding of these enzymes to lignin [52-56]. …”

- Synthetic Biology: A Promising Technology for Biofuel Production

“…Furthermore, woody biomass is generally more resistant to degradation than other types of lignocellulose. Softwood is typically more difficult to hydrolyze than hardwood or agricultural residues [8][9][10][11][12].…”