Genetically Engineered Escherichia coli FBR5 to Use Cellulosic Sugars: Production of Ethanol from Corn Fiber Hydrolyzate Employing Commercial Nutrient Medium

N. Qureshi, B. S. Dien, B. C. Saha, L. Iten, S. Liu, S. R. Hughes


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.

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