Biosynthesis of Ethanol and Hydrogen by Glycerol Fermentation Using Escherichia coli

Abstract

Prodn. of high value products from glycerol via anaerobic fermn. is of utmost importance for the biodiesel industry. The microorganism Escherichia coli (E. coli) K12 was used for fermn. of glycerol. The effects of glycerol concn. and headspace conditions on the cell growth, ethanol and hydrogen prodn. were investigated. A full factorial exptl. design with 3 replicates was conducted in order to test these factors. Under the three headspace conditions tested, the increase of glycerol concn. accelerated glycerol fermn. The yields of hydrogen and ethanol were the lowest when glycerol concn. of 10 g/L was used. The max. prodn. of hydrogen was obsd. with an initial glycerol concn. of 25 g/L at a final concn. of hydrogen was 32.15 mmol/L. This study demonstrated that hydrogen prodn. neg. affects cell growth. Maximum ethanol yield was obtained with a glycerol concn. of 10 g/L and was up to 0.40 g/g glycerol under membrane condition headspace. Statistical optimization showed that optimal conditions for hydrogen prodn. are 20 g/L initial glycerol with initial sparging of the reactor headspace. The optimal conditions for ethanol prodn. are 10 g/L initial glycerol with membrane. [on SciFinder(R)]