title: Combining treatments to improve the fermentation of sugarcane bagasse hydrolysates by ethanologenic Escherichia coli LY180.
abstract: Inhibitory side products from dilute acid pretreatment is a major challenge for conversion of lignocellulose into ethanol. Six strategies to detoxify sugarcane hydrolysates were investigated alone, and in combinations (vacuum evaporation of volatiles, high pH treatment with ammonia, laccase, bisulfite, microaeration, and inoculum size). High pH was the most beneficial single treatment, increasing the minimum inhibitory concentration (measured by ethanol production) from 15% (control) to 70% hydrolysate. Combining treatments provided incremental improvements, consistent with different modes of action and multiple inhibitory compounds. Screening toxicity using tube cultures proved to be an excellent predictor of relative performance in pH-controlled fermenters. A combination of treatments (vacuum evaporation, laccase, high pH, bisulfite, microaeration) completely eliminated all inhibitory activity present in hydrolysate. With this combination, fermentation of hemicellulose sugars (90% hydrolysate) to ethanol was complete within 48 h, identical to the fermentation of laboratory xylose (50 g/L) in AM1 mineral salts medium (without hydrolysate).
authors: Department of Microbiology & Cell Science, University of Florida, Box 110700, Gainesville, FL 32611, USA. Electronic address: rgeddes@ufl.edu.
authors: Ryan
authors: R
authors: Geddes
authors: Department of Microbiology & Cell Science, University of Florida, Box 110700, Gainesville, FL 32611, USA. Electronic address: shan@ufl.edu.
authors: Keelnatham T
authors: KT
authors: Shanmugam
authors: Department of Microbiology & Cell Science, University of Florida, Box 110700, Gainesville, FL 32611, USA. Electronic address: ingram@ufl.edu.
authors: Lonnie O
authors: LO
authors: Ingram
mesh_terms: D000332:Aerobiosis / Q000187:drug effects; D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology / Q000379:methods*; D002241:Carbohydrates / Q000494:pharmacology; D002482:Cellulose / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects; D005662:Furaldehyde / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D031786:Saccharum / Q000378:metabolism*; D014618:Vacuum; D014835:Volatilization
chemical_list: D002241:Carbohydrates; D000431:Ethanol; D002482:Cellulose; C027433:bagasse; D005662:Furaldehyde
keywords: Ethanol; Furfural; Hemicellulose; Hydrolysate; Inhibitors