title: Effect of primary degradation-reaction products from Ammonia Fiber Expansion (AFEX)-treated corn stover on the growth and fermentation of Escherichia coli KO11.
abstract: The primary degradation-reaction products (DRP) identified in Ammonia Fiber Expansion (AFEX)-pretreated corn stover are acetate, lactate, 4-hydroxybenzaldehyde (4HBD) and acetamide. The effects of these products at a broad concentration range were tested on Escherichia coli KO11, a strain engineered for cellulosic ethanol production. Fermentations using glucose or xylose as the sole carbohydrate source and a sugar mixture of glucose and xylose were conducted to determine how these products and sugar selection affected fermentation performance. Co-fermentation of the sugar mixture exhibited the lowest overall ethanol productivity compared to single-sugar fermentations and was more susceptible to inhibition. Metabolic ethanol yield increased with the increasing initial concentration of acetate. Although these degradation-reaction products (with exception of acetamide) are generally perceived to be inhibitory, organic acids and 4-hydroxybenzaldehyde at low levels stimulated fermentation. Adaptation of cells to these products prior to fermentation increased overall fermentation rate.
authors.affiliation: Department of Chemical Engineering and Materials Science, DOE Great Lakes Bioenergy Research Center, Michigan State University, 3900 Collins Rd., Lansing, MI 48910, USA.
authors.forename: Ming W
authors.initials: MW
authors.lastname: Lau
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Dale
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D005285:Fermentation; D014994:Xylose / Q000378:metabolism; D003313:Zea mays
chemical_list: D000641:Ammonia; D014994:Xylose