title: Cellulosic ethanol: interactions between cultivar and enzyme loading in wheat straw processing.
abstract: BACKGROUND
  Variations in sugar yield due to genotypic qualities of feedstock are largely undescribed for pilot-scale ethanol processing. Our objectives were to compare glucose and xylose yield (conversion and total sugar yield) from straw of five winter wheat cultivars at three enzyme loadings (2.5, 5 and 10 FPU g-1 dm pretreated straw) and to compare particle size distribution of cultivars after pilot-scale hydrothermal pretreatment.
  
  
  RESULTS
  Significant interactions between enzyme loading and cultivars show that breeding for cultivars with high sugar yields under modest enzyme loading could be warranted. At an enzyme loading of 5 FPU g-1 dm pretreated straw, a significant difference in sugar yields of 17% was found between the highest and lowest yielding cultivars. Sugar yield from separately hydrolyzed particle-size fractions of each cultivar showed that finer particles had 11% to 21% higher yields than coarse particles. The amount of coarse particles from the cultivar with lowest sugar yield was negatively correlated with sugar conversion.
  
  
  CONCLUSIONS
  We conclude that genetic differences in sugar yield and response to enzyme loading exist for wheat straw at pilot scale, depending on differences in removal of hemicellulose, accumulation of ash and particle-size distribution introduced by the pretreatment.
authors.affiliation: Plant and Soil Science Laboratory, Department of Agriculture and Ecology, Faculty of Life Sciences, University of Copenhagen, Denmark. lindedam@life.ku.dk.
authors.forename: Jane
authors.initials: J
authors.lastname: Lindedam
authors.forename: Sander
authors.initials: S
authors.lastname: Bruun
authors.forename: Henning
authors.initials: H
authors.lastname: Jørgensen
authors.forename: Claus
authors.initials: C
authors.lastname: Felby
authors.forename: Jakob
authors.initials: J
authors.lastname: Magid