title: Surface properties correlate to the digestibility of hydrothermally pretreated lignocellulosic Poaceae biomass feedstocks.
abstract: BACKGROUND
  Understanding factors that govern lignocellulosic biomass recalcitrance is a prerequisite for designing efficient 2nd generation biorefining processes. However, the reasons and mechanisms responsible for quantitative differences in enzymatic digestibility of various biomass feedstocks in response to hydrothermal pretreatment at different severities are still not sufficiently understood.
  
  
  RESULTS
  Potentially important lignocellulosic feedstocks for biorefining, corn stover (Zea mayssubsp.maysL.), stalks ofMiscanthus×giganteus, and wheat straw (Triticum aestivumL.) were systematically hydrothermally pretreated; each at three different severities of 3.65, 3.83, and 3.97, respectively, and the enzymatic digestibility was assessed. Pretreated samples ofMiscanthus×giganteusstalks were the least digestible among the biomass feedstocks producing ~24 to 66.6% lower glucose yields than the other feedstocks depending on pretreatment severity and enzyme dosage. Bulk biomass composition analyses, 2D nuclear magnetic resonance, and comprehensive microarray polymer profiling were not able to explain the observed differences in recalcitrance among the pretreated feedstocks. However, methods characterizing physical and chemical features of the biomass surfaces, specifically contact angle measurements (wettability) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy (surface biopolymer composition) produced data correlating pretreatment severity and enzymatic digestibility, and they also revealed differences that correlated to enzymatic glucose yield responses among the three different biomass types.
  
  
  CONCLUSIONS
  The study revealed that to a large extent, factors related to physico-chemical surface properties, namely surface wettability as assessed by contact angle measurements and surface content of hemicellulose, lignin, and wax as assessed by ATR-FTIR rather than bulk biomass chemical composition correlated to the recalcitrance of the tested biomass types. The data provide new insight into how hydrothermal pretreatment severity affects surface properties of key Poaceae lignocellulosic biomass and may help design new approaches to overcome biomass recalcitrance.
authors.affiliation: Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads Building 229, 2800 Kongens Lyngby, Denmark.
authors.forename: Demi T
authors.identifier: 0000-0002-4131-3228
authors.initials: DT
authors.lastname: Djajadi
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Kongens Lyngby, Denmark.
authors.forename: Aleksander R
authors.initials: AR
authors.lastname: Hansen
authors.affiliation: Department of Geosciences and Natural Resource Management, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg C, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Jensen
authors.affiliation: Department of Geosciences and Natural Resource Management, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg C, Denmark.
authors.forename: Lisbeth G
authors.initials: LG
authors.lastname: Thygesen
authors.affiliation: Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads Building 229, 2800 Kongens Lyngby, Denmark.
authors.forename: Manuel
authors.initials: M
authors.lastname: Pinelo
authors.affiliation: Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads Building 229, 2800 Kongens Lyngby, Denmark.
authors.forename: Anne S
authors.identifier: 0000-0001-8910-9931
authors.initials: AS
authors.lastname: Meyer
authors.affiliation: Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads Building 229, 2800 Kongens Lyngby, Denmark.|Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Kongens Lyngby, Denmark.
authors.forename: Henning
authors.initials: H
authors.lastname: Jørgensen
keywords: 2D nuclear magnetic resonance (NMR); Attenuated total reflectance-Fourier transform infrared (ATR-FTIR); Comprehensive microarray polymer profiling (CoMPP); Contact angle measurements; Enzymatic hydrolysis; Hemicellulose; Hydrothermal pretreatment; Wettability