GENETICALLY ENGINEERED ESCHERICHIA COLI FBR5 TO USE CELLULOSIC SUGARS: PRODUCTION OF ETHANOL FROM CORN FIBER HYDROLYZATE EMPLOYING COMMERCIAL NUTRIENT MEDIUM

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 -1 h -1 , respectively. Corn fiber (CF) was pretreated with dilute H 2 SO 4 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 -1 h -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.