title: Rapid estimation of sugar release from winter wheat straw during bioethanol production using FTIR-photoacoustic spectroscopy.
abstract: BACKGROUND
  Complexity and high cost are the main limitations for high-throughput screening methods for the estimation of the sugar release from plant materials during bioethanol production. In addition, it is important that we improve our understanding of the mechanisms by which different chemical components are affecting the degradability of plant material. In this study, Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) was combined with advanced chemometrics to develop calibration models predicting the amount of sugars released after pretreatment and enzymatic hydrolysis of wheat straw during bioethanol production, and the spectra were analysed to identify components associated with recalcitrance.
  
  
  RESULTS
  A total of 1122 wheat straw samples from nine different locations in Denmark and one location in the United Kingdom, spanning a large variation in genetic material and environmental conditions during growth, were analysed. The FTIR-PAS spectra of non-pretreated wheat straw were correlated with the measured sugar release, determined by a high-throughput pretreatment and enzymatic hydrolysis (HTPH) assay. A partial least square regression (PLSR) calibration model predicting the glucose and xylose release was developed. The interpretation of the regression coefficients revealed a positive correlation between the released glucose and xylose with easily hydrolysable compounds, such as amorphous cellulose and hemicellulose. Additionally, a negative correlation with crystalline cellulose and lignin, which inhibits cellulose and hemicellulose hydrolysis, was observed.
  
  
  CONCLUSIONS
  FTIR-PAS was used as a reliable method for the rapid estimation of sugar release during bioethanol production. The spectra revealed that lignin inhibited the hydrolysis of polysaccharides into monomers, while the crystallinity of cellulose retarded its hydrolysis into glucose. Amorphous cellulose and xylans were found to contribute significantly to the released amounts of glucose and xylose, respectively.
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg, C DK-1871 Denmark.
authors.forename: Georgios
authors.initials: G
authors.lastname: Bekiaris
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg, C DK-1871 Denmark.
authors.forename: Jane
authors.initials: J
authors.lastname: Lindedam
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg, C DK-1871 Denmark.
authors.forename: Clément
authors.initials: C
authors.lastname: Peltre
authors.affiliation: National Renewable Energy Laboratory, Biosciences Center, 15013 Denver West Parkway, Golden, Colorado 80401 USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Decker
authors.affiliation: National Renewable Energy Laboratory, Biosciences Center, 15013 Denver West Parkway, Golden, Colorado 80401 USA.
authors.forename: Geoffrey B
authors.initials: GB
authors.lastname: Turner
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg, C DK-1871 Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Magid
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg, C DK-1871 Denmark.
authors.forename: Sander
authors.initials: S
authors.lastname: Bruun
keywords: Advanced chemometrics; Bioethanol production; Enzymatic hydrolysis; FTIR-photoacoustic spectroscopy; High-throughput assay; Prediction; Pretreatment; Sugar release