| 초록 |
Hydrogen is considered a potential fuel of the future. Biologically, H2 can be produced from many raw materials including carbon monoxide (CO). The CO-dependent H2 production, so-called water-gas shift reaction (WGSR), is widely spread among phototrophic bacteria and archea. Citrobacter amalonaticus Y19 (Y19), a chemoheterotrophic Enterobacter can perform WGSR efficiently. The contig genome sequencing of Y19 exhibited the presence of a unique CO oxidizing gene cluster encoding carbon monoxide dehydrogenase (CODH; cooFS), CO-dependent hydrogenase (CO-hyd; cooMKLXUH) and a putative CO-responsive transcriptional activator (cooA-1). In order to elevate its potential as a whole cell-biocatalyst for CO-dependent H2 production, we developed a recombinant overexpressing cooA-1. It showed 1.9 fold improvement in whole-cell H2 production activity than the wild type strain. Further, cell homogenates exhibited improved CODH and CO-hyd activities by 1.6- and 2.2- fold respectively. This study confirms that cooA-1 in Y19 is a positive regulator for CODH and CO-hyd operons, the overexpression of which greatly improved the CO-dependent H2 production activity in Y19. |
