Title: The effect of alkali-soluble lignin on purified core cellulase and hemicellulase activities during hydrolysis of extractive ammonia-pretreated lignocellulosic biomass

Abstract

Removing alkali-soluble lignin using extractive ammonia (EA) pretreatment of corn stover (CS) is known to improve biomass conversion efficiency during enzymatic hydrolysis. In this study, we investigated the effect of alkali-soluble lignin on six purified core glycosyl hydrolases and their enzyme synergies, adopting 31 enzyme combinations derived by a five-component simplex centroid model, during EA-CS hydrolysis. Hydrolysis experiment was carried out using EA-CS(-) (approx. 40% lignin removed during EA pretreatment) and EA-CS(+) (where no lignin was extracted). Enzymatic hydrolysis experiments were done at three different enzyme mass loadings (7.5, 15 and 30 mg protein g^-1 glucan), using a previously developed high-throughput microplate-based protocol, and the sugar yields of glucose and xylose were detected. The optimal enzyme combinations (based on % protein mass loading) of six core glycosyl hydrolases for EA-CS(-) and EA-CS(+) were determined that gave high sugar conversion. The inhibition of lignin on optimal enzyme ratios was studied, by adding fixed amount of alkali-soluble lignin fractions to EA-CS(-), and pure Avicel, beechwood xylan and evaluating their sugar conversion. The optimal enzyme ratios that gave higher sugar conversion for EA-CS(-) were CBH I: 27.2–28.2%, CBH II: 18.2–22.2%, EG I: 29.2–34.3%, EX: 9.0–14.1%, βX: 7.2–10.2%, βG: 1.0–5.0% (at 7.5–30 mg g^-1more » protein mass loading). Endoglucanase was inhibited to a greater extent than other core cellulases and xylanases by lignin during enzyme hydrolysis. We also found that alkali-soluble lignin inhibits cellulase more strongly than hemicellulase during the course of enzyme hydrolysis.« less

Authors:

Zhou, Linchao ^[1]; da Costa Sousa, Leonardo ^[2]; Dale, Bruce E. ^[3]; Feng, Jia-Xun ^[4]; Balan, Venkatesh  ^[5]

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+ Show Author Affiliations

1. Guangxi Univ., Nanning (China). State Key Lab. for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology
2. Michigan State Univ., East Lansing, MI (United States). DOE Great Lakes Bioenergy Research Center (GLBRC), Biomass Conversion Research Laboratory (BCRL), Dept. of Chemical Engineering and Materials Science
3. Michigan State Univ., East Lansing, MI (United States). DOE Great Lakes Bioenergy Research Center (GLBRC), Biomass Conversion Research Laboratory (BCRL), Dept. of Chemical Engineering and Materials Science
4. Guangxi Univ., Nanning (China). State Key Lab. for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology
5. Michigan State Univ., East Lansing, MI (United States). DOE Great Lakes Bioenergy Research Center (GLBRC), Biomass Conversion Research Laboratory (BCRL), Dept. of Chemical Engineering and Materials Science; Univ. of Houston, Houston, TX (United State). Dept. of Engineering Technology, Biotechnology Division, School of Technology

Publication Date:

2018-06-27

Research Org.:

Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1499908

Grant/Contract Number:  

FC02-07ER64494

Resource Type:

Accepted Manuscript

Journal Name:

Royal Society Open Science

Additional Journal Information:

Journal Volume: 5; Journal Issue: 6; Journal ID: ISSN 2054-5703

Publisher:

The Royal Society Publishing

Country of Publication:

United States

Language:

English

Subject:

09 BIOMASS FUELS; ammonia treatment; lignin inhibition; cellulase; hemicellulase; enzyme synergy