Metabolic flux analysis of biological hydrogen production by Escherichia coli

For hydrogen to be a viable energy carrier, it is essential to generate it from renewable sources. A promising route is hydrogen generation from biological methods. However, the low yield of hydrogen is a constraint. Significant improvement in the yield is expected through genetic modification of the microorganism. Metabolic flux analysis (MFA) can be used to analyze the effect of genetic modification on the yield a priori.In this paper MFA has been applied to hydrogen production using growth of Escherichia coli on glucose. Flux analysis was carried out on experimental data from literature. Hydrogen production using parent strain was 0.17 mol per mole of glucose consumed. It increased to 0.23 mol for the strain lacking lactate dehydrogenase. MFA was also used to determine the feasible operating space for hydrogen production against the varying yields of other metabolites. It was found that production of ethanol and acetate is necessary for hydrogen production, while production of succinate and lactate is not necessary.