Probing the nature of AFEX-pretreated corn stover derived decomposition products that inhibit cellulase activity

James F Humpula; Nirmal Uppugundla; Ramin Vismeh; Leonardo Sousa; Shishir P S Chundawat; A Daniel Jones; Venkatesh Balan; Bruce E Dale; Albert M Cheh

doi:10.1016/j.biortech.2013.10.082

Probing the nature of AFEX-pretreated corn stover derived decomposition products that inhibit cellulase activity

Bioresour Technol. 2014:152:38-45. doi: 10.1016/j.biortech.2013.10.082. Epub 2013 Nov 1.

Authors

James F Humpula¹, Nirmal Uppugundla¹, Ramin Vismeh², Leonardo Sousa¹, Shishir P S Chundawat³, A Daniel Jones², Venkatesh Balan¹, Bruce E Dale¹, Albert M Cheh⁴

Affiliations

¹ Biomass Conversion Research Laboratory, Chemical Engineering and Materials Science, Michigan State University, Lansing, MI 48824, USA; DOE-Great Lakes Bioenergy Research Center (GLBRC), Michigan State University, East Lansing, MI 48824, USA.
² DOE-Great Lakes Bioenergy Research Center (GLBRC), Michigan State University, East Lansing, MI 48824, USA; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
³ Biomass Conversion Research Laboratory, Chemical Engineering and Materials Science, Michigan State University, Lansing, MI 48824, USA; DOE-Great Lakes Bioenergy Research Center (GLBRC), Michigan State University, East Lansing, MI 48824, USA; Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
⁴ Department of Environmental Science, American University, Washington, DC 20016, USA. Electronic address: acheh@american.edu.

PMID: 24275024
DOI: 10.1016/j.biortech.2013.10.082

Abstract

Sequential fractionation of AFEX-pretreated corn stover extracts was carried out using ultra-centrifugation, ultra-filtration, and solid phase extraction to isolate various classes of pretreatment products to evaluate their inhibitory effect on cellulases. Ultra-centrifugation removed dark brown precipitates that caused no appreciable enzyme inhibition. Ultra-filtration of ultra-centrifuged AFEX-pretreated corn stover extractives using a 10 kDa molecular weight cutoff (MWCO) membrane removed additional high molecular weight components that accounted for 24-28% of the total observed enzyme inhibition while a 3 kDa MWCO membrane removed 60-65%, suggesting significant inhibition is caused by oligomeric materials. Solid phase extraction (SPE) of AFEX-pretreated corn stover extractives after ultra-centrifugation removed 34-43% of the inhibition; ultra-filtration with a 5 kDa membrane removed 44-56% of the inhibition and when this ultra-filtrate was subjected to SPE a total of 69-70% of the inhibition were removed. Mass spectrometry found several phenolic compounds among the hydrophobic inhibition removed by SPE adsorption.

Keywords: AFEX; AFEX-CS; AFEX-CS-E; AFEX-treated corn stover; Cellulase; Fractionation; Inhibition; MP; MX; Multifect Pectinase; Multifect Xylanase; SPE; UC; UC-AFEX-CS-E; UF; UF-UC-AFEX-CS-E; Ultra-filtration; aqueous extract of AFEX-treated corn stover; solid phase extraction; ultra-centrifugation; ultra-centrifuged and ultra-filtered aqueous extract of AFEX-treated corn stover; ultra-centrifuged extract of AFEX treated corn stover; ultra-filtration.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Ammonia / pharmacology*
Biotechnology / methods*
Cellulases / antagonists & inhibitors*
Cellulases / metabolism
Cellulose / metabolism
Chemical Fractionation
Chromatography, Liquid
Enzyme Inhibitors / isolation & purification
Enzyme Inhibitors / pharmacology*
Glucans / metabolism
Mass Spectrometry
Oligosaccharides / analysis
Solid Phase Extraction
Ultracentrifugation
Ultrafiltration
Waste Products*
Zea mays / drug effects*

Substances

Enzyme Inhibitors
Glucans
Oligosaccharides
Waste Products
Ammonia
Cellulose
Cellulases