title: Physical and chemical differences between one-stage and two-stage hydrothermal pretreated hardwood substrates for use in cellulosic ethanol production.
abstract: BACKGROUND
  There are many different types of pretreatment carried out to prepare cellulosic substrates for fermentation. In this study, one- and two-stage hydrothermal pretreatment were carried out to determine their effects on subsequent fermentations. The two substrates were found to behave differently during fermentation. The two substrates were then characterized using physical and chemical parameters.
  
  
  RESULTS
  The one-stage substrate was found to have higher carbohydrate content and lower lignin content. It exhibited a higher level of viscosity, a larger settled volume, and a slower settling time than the two-stage substrate. It also showed higher polarity and reduced crystallinity. Glycome profiling showed physical differences between the two substrates, specifically pointing toward higher levels of pectin and hemicellulose in the one-stage substrate (MS1112) as compared to the two-stage substrate (MS1107).
  
  
  CONCLUSIONS
  We hypothesize that these physical and chemical differences between the substrates contribute to the differences seen during fermentation including: ethanol yield, ethanol titer, fermentation rate, fermentation completion time, mixing, and substrate solubilization. These findings can be used in optimizing pretreatment parameters to maximize ethanol conversion and overall process yield for hardwood substrates.
authors: Mascoma LLC, 67 Etna Road, Lebanon, NH 03766 USA ; Lallemand, 8215 Beachwood Road, Baltimore, MD 21222 USA.
authors: Andrew
authors: A
authors: Guilliams
authors: CCRC, 315 Riverbend Road, Athens, GA 30602 USA.
authors: Sivakumar
authors: S
authors: Pattathil
authors: Mascoma LLC, 67 Etna Road, Lebanon, NH 03766 USA ; Lallemand, 8215 Beachwood Road, Baltimore, MD 21222 USA.
authors: Deidre
authors: D
authors: Willies
authors: Mascoma LLC, 67 Etna Road, Lebanon, NH 03766 USA ; Lallemand, 8215 Beachwood Road, Baltimore, MD 21222 USA.
authors: Matt
authors: M
authors: Richards
authors: Georgia Tech Renewable Bioproducts Institute, 500 10th Street NW, Atlanta, GA 230332 USA.
authors: Yunqiao
authors: Y
authors: Pu
authors: CCRC, 315 Riverbend Road, Athens, GA 30602 USA.
authors: Sindhu
authors: S
authors: Kandemkavil
authors: Mascoma LLC, 67 Etna Road, Lebanon, NH 03766 USA ; Lallemand, 8215 Beachwood Road, Baltimore, MD 21222 USA.
authors: Erin
authors: E
authors: Wiswall
keywords: Biofuels; Cellulosic ethanol; Glycome profiling; Hardwood fermentation; Pretreatment