Enhancing the Enzymatic Hydrolysis of Corn Stover by an Integrated Wet-milling and Alkali Pretreatment

Abstract

An integrated wet-milling and alkali pretreatment was applied to corn stover prior to enzymatic hydrolysis. The effects of NaOH concentration in the pretreatment on crystalline structure, chemical composition, and reducing-sugar yield of corn stover were investigated, and the mechanism of increasing reducing-sugar yield by the pretreatment was discussed. The experimental results showed that the crystalline structure of corn stover was disrupted, and lignin was removed, while cellulose and hemicellulose were retained in corn stover by the pretreatment with 1% NaOH in 1 h. The reducing-sugar yield from the pretreated corn stovers increased from 20.2% to 46.7% when the NaOH concentration increased from 0% to 1%. The 1% NaOH pretreated corn stover had a holocellulose conversion of 55.1%. The increase in reducing-sugar yield was related to the crystalline structure disruption and delignification of corn stover. It was clarified that the pretreatment significantly enhanced the conversion of cellulose and hemicellulose in the corn stover to sugars.

Enhanced saccharification of corn straw pretreated by alkali combining crude ligninolytic enzymes

“…However, our results also showed that if lignin is the target at this stage, all three pretreatments, NaOH 1.5% alone, NaOH 2% alone and NaOH 1.5% with crude enzyme can be efficient. This was in good agreement with the study of He et al, 53 who reported that increase in NaOH concentration from 1% to 2% did not significantly improve delignification of corn straw.…”

Process Modeling of Enzymatic Hydrolysis of Wet-Exploded Corn Stover

“…Optimal process conditions for enzymatic hydrolysis to high glucose included both high SC and low enzyme loading. This is a remarkable improvement over previous studies done with pretreated corn stover either at low SC (<10 %) or high enzyme loading (>10 FPU, equivalent to 30 mg EP/g glucan) to achieve higher cellulose conversion [5,6,18,19]. By increasing the SC, the glucose yield improved significantly.…”

Simultaneous Saccharification and Fermentation of Ground Corn Stover for the Production of Fuel Ethanol Using Phanerochaete chrysosporium, Gloeophyllum trabeum, Saccharomyces cerevisiae, and Escherichia coli K011

“…1. Unlike the SSF process in previous works, ours does not use pretreated corn stover samples [13,19,25,42] or the addition of expensive commercial enzymes [12,26,53]. Instead, cellulases and hemicellulases are produced by G. trabeum and P. chrysosporium in situ upon corn stover enzyme induction performed via solid substrate fermentation in a pH range of 4.5-4.8 at 37 o C for 4 days, conditions that are suitable not only for the growth of the fungi but also for production of cellulolytic enzymes [38,43,44].…”

“…Pretreatment of plant biomass is crucial for the production of cellulosic ethanol as it greatly improves the enzymatic accessibility of the feedstock [13,19,25,41,42]. In recent years, several pretreatment methods have been tested on corn stover that involve physical, chemical, or physicochemical procedures or a combination thereof [16,47,56].…”