Applications of bacterial hydrogenases in waste decontamination, manufacture of novel bionanocatalysts and in sustainable energy

Bacterial hydrogenases have been harnessed to the removal of heavy metals from solution by reduction to less soluble metal species. For Pd(II), its bioreduction results in the deposition of cell-bound Pd(0)-nanoparticles that are ferromagnetic and have a high catalytic activity. Hydrogenases can also be used synthetically in the production of hydrogen from sugary wastes through breakdown of formate produced by fermentation. The Bio-H₂ produced can be used to power an electrical device using a fuel cell to provide clean electricity. Production of hydrogen from confectionery wastes by one organism (Escherichia coli) can be used as the electron donor for the production of Bio-Pd⁰ from soluble Pd(II) by a second organism. The resulting Bio-Pd⁰ can then be used as a bioinorganic catalyst in the remediation of Cr(VI)-contaminated solutions or polychlorinated biphenyls at the expense of Bio-H₂, as a hydrogenation catalyst for industry or as a component of a fuel cell electrode.