title: Probing the nature of AFEX-pretreated corn stover derived decomposition products that inhibit cellulase activity.
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.
authors.affiliation: 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.
authors.forename: James F
authors.initials: JF
authors.lastname: Humpula
authors.affiliation: 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.
authors.forename: Nirmal
authors.initials: N
authors.lastname: Uppugundla
authors.affiliation: 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.
authors.forename: Ramin
authors.initials: R
authors.lastname: Vismeh
authors.affiliation: 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.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Sousa
authors.affiliation: 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.
authors.forename: Shishir P S
authors.initials: SP
authors.lastname: Chundawat
authors.affiliation: 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.
authors.forename: A Daniel
authors.initials: AD
authors.lastname: Jones
authors.affiliation: 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.
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Balan
authors.affiliation: 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.
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Dale
authors.affiliation: Department of Environmental Science, American University, Washington, DC 20016, USA. Electronic address: acheh@american.edu.
authors.forename: Albert M
authors.initials: AM
authors.lastname: Cheh
mesh_terms: D000641:Ammonia / Q000494:pharmacology*; D001709:Biotechnology / Q000379:methods*; D044602:Cellulases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D005591:Chemical Fractionation; D002853:Chromatography, Liquid; D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D005936:Glucans / Q000378:metabolism; D013058:Mass Spectrometry; D009844:Oligosaccharides / Q000032:analysis; D052616:Solid Phase Extraction; D014461:Ultracentrifugation; D014462:Ultrafiltration; D014866:Waste Products; D003313:Zea mays / Q000187:drug effects*
chemical_list: D004791:Enzyme Inhibitors; D005936:Glucans; D009844:Oligosaccharides; D014866:Waste Products; D000641:Ammonia; D002482:Cellulose; D044602:Cellulases
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