Enhanced hydrogen production from glucose using ldh- and frd-inactivated Escherichia coli strains

Abstract

We improved the hydrogen yield from glucose using a genetically modified Escherichia coli. E. coli strain SR15 (ΔldhA, ΔfrdBC), in which glucose metabolism was directed to pyruvate formate lyase (PFL), was constructed. The hydrogen yield of wild-type strain of 1.08 mol/mol glucose, was enhanced to 1.82 mol/mol glucose in strain SR15. This figure is greater than 90 % of the theoretical hydrogen yield of facultative anaerobes (2.0 mol/mol glucose). Moreover, the specific hydrogen production rate of strain SR15 (13.4 mmol h-1 g-1 dry cell) was 1.4-fold higher than that of wild-type strain. In addition, the volumetric hydrogen production rate increased using the process where cells behaved as an effective catalyst. At 94.3 g dry cell/l, a productivity of 793 mmol h-1 l-1 (20.2 l h -1 l-1 at 37°C) was achieved using SR15. The reported productivity substantially surpasses that of conventional biological hydrogen production processes and can be a trigger for practical applications. © 2006 Springer-Verlag.