Optimization and interaction of media components in ethanol production using Zymomonas mobilis by response surface methodology

Ethanol production using Zymomonas mobilis strains with medium optimized by response surface methodology (RSM) was studied. A significant improvement in the ethanol yield (0.50g/g ethanol) was demonstrated, resulting in very low residual sugar and fewer by-products. The five-factor and five-response full factorial design have shown that glucose and yeast extract are the he y media components that influence ethanol production, follow-ed by the inoc ulum concentration and ammonium sulfate, with phosphate showing Little or n o effect. The composition tall in g/l of the optimized medium was glucose 1 20.4, ammonium sulfate 0.96, potassium dihydrogen phosphate 0.02, yeast ext ract 6.5, and magnesium sulfate 0.5. The optimum inoculum concentration was log(10) 8.4 cells.