title: Effect of compositional variability of distillers' grains on cellulosic ethanol production.
abstract: In a dry grind ethanol plant, approximately 0.84kg of dried distillers' grains with solubles (DDGS) is produced per liter of ethanol. The distillers' grains contain the unhydrolyzed and unprocessed cellulosic fraction of corn kernels, which could be further converted to ethanol or other valuable bioproducts by applying cellulose conversion technology. Its compositional variability is one of the factors that could affect the overall process design and economics. In this study, we present compositional variability of distillers' grains collected from four different dry grind ethanol plants and its effect on enzymatic digestibility and fermentability. We then selected two sources of distillers grains based on their distinctive compositional difference. These were pretreated by either controlled pH liquid hot water (LHW) or ammonia fiber expansion (AFEX) and subjected to enzymatic hydrolysis and fermentation. Fermentation of the pretreated distillers' grains using either industrial yeast or genetically engineered glucose and xylose co-fermenting yeast, yielded 70-80% of theoretical maximum ethanol concentration, which varied depending on the batch of distillers' grains used. Results show that cellulose conversion and ethanol fermentation yields are affected by the compositions of distillers' grains. Distillers' grains with a high extractives content exhibit a lower enzymatic digestibility but a higher fermentability.
authors.affiliation: Laboratory of Renewable Resources Engineering, Potter Engineering Center, 500 Central Drive, Purdue University, West Lafayette, IN 47907-2022, United States.
authors.forename: Youngmi
authors.initials: Y
authors.lastname: Kim
authors.forename: Rick
authors.initials: R
authors.lastname: Hendrickson
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Mosier
authors.forename: Michael R
authors.initials: MR
authors.lastname: Ladisch
authors.forename: Bryan
authors.initials: B
authors.lastname: Bals
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Balan
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Dale
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Dien
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cotta
mesh_terms: D000641:Ammonia / Q000737:chemistry; D001709:Biotechnology / Q000379:methods*; D002482:Cellulose / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002523:Edible Grain / Q000737:chemistry*; D004798:Enzymes / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry*; D005285:Fermentation; D005947:Glucose / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D015203:Reproducibility of Results; D012995:Solubility; D014867:Water / Q000737:chemistry; D014994:Xylose / Q000737:chemistry
chemical_list: D004798:Enzymes; D014867:Water; D000431:Ethanol; D000641:Ammonia; D002482:Cellulose; D014994:Xylose; D005947:Glucose