Location: Bioenergy ResearchTitle: Genetically engineered Escherichia coli FBR5 to use cellulosic sugars: Production of ethanol from corn fiber hydrolyzate employing commercial nutrient medium
Submitted to: European Chemical Bulletin
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2015
Publication Date: 3/10/2015
Publication URL: http://www.eurchembull.com/index.php/ECB/article/view/1601
Citation: Qureshi, N., Dien, B.S., Saha, B.C., Iten, L., Liu, S., Hughes, S.R. 2015. Genetically engineered Escherichia coli FBR5 to use cellulosic sugars: Production of ethanol from corn fiber hydrolyzate employing commercial nutrient medium. European Chemical Bulletin. 4(3):130-134. doi: 10.17628/ECB.2015.4.130.
Interpretive Summary: Ethanol is an alternative biofuel that can be used in automobiles. In the United States approximately 13.3 billion gallons of ethanol was produced in 2013 from corn. In order to meet nation’s annual transportation fuel demand (138 billion gallons) it is necessary to produce more biofuel from renewable resources such as agricultural products. However, further increase in ethanol production from corn is not possible as it creates food and feed vs. fuel competition thus increasing food and feed prices. For this reason ethanol should be produced from economically available agricultural residues such as corn fiber and other cheap agriculture based nutrients such as corn steep liquor (a by-product of corn wet milling process), and soy peptone (soy protein hydrolyzate). In these studies we produced ethanol from corn fiber and soy peptone. Production of ethanol would not only bring us closer to independence from foreign oil, it will also be economical to produce it from our agricultural residues and biomass. Development of this process would benefit transportation industry, U.S. farmers, and the U.S. public.
Technical Abstract: Transportation biofuel ethanol was produced from xylose and corn fiber hydrolyzate (CFH) in a batch reactor employing Escherichia coli FBR5. This strain was previously developed in our laboratory to use cellulosic sugars. The culture can produce up to 49.32 gL-1 ethanol from approximately 125 gL-1 xylose. Use of commercial nutrient sources such as corn steep liquor (CSL) and soy peptone (SP) was also studied and SP was found to be superior than CSL. SP at a concentration of 15 gL-1 resulted in the production of 42.2 gL-1 ethanol with ethanol yield and productivity of 0.49 and 0.74 gL-1h-1, respectively. Corn fiber (CF) was pretreated with dilute H2SO4 and hydrolyzed using commercial cellulases. Employing CFH as a sole substrate, the culture produced 35.33 gL-1 ethanol with a productivity and yield of 1.01 gL-1h-1 and 0.54, respectively, leaving behind no residual sugars in the medium. This productivity is 40% higher than when using xylose as the carbon source in the control experiment.