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-H(2) 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-Pd(0) from soluble Pd(II) by a second organism. The resulting Bio-Pd(0) can then be used as a bioinorganic catalyst in the remediation of Cr(VI)-contaminated solutions or polychlorinated biphenyls at the expense of Bio-H(2), as a hydrogenation catalyst for industry or as a component of a fuel cell electrode.

Production of H2 from sucrose by Escherichia coli strains carrying the pUR400 plasmid, which encodes invertase activity.

Escherichia coli HD701, a hydrogenase-upregulated strain, has the potential for industrial-scale H2 production but is unable to metabolise sucrose, which is a major constituent of many waste materials that could be used as feedstocks for H2 production processes. A 70 kb plasmid (pUR400), which carries the genes necessary for sucrose transport into the cell and its metabolism, was conjugated into E. coli strains HD701 and FTD701 [a derivative of HD701 which has a deletion of the tatC gene of the twin arginine transport (Tat) protein system] from an E. coli K12 strain. Comparative studies on H2 evolution by FTD701 and HD701, with and without the pUR400 plasmid, were made using sucrose as substrate. The parental strains did not evolve H2, although HD701/pUR400 and FTD701/pUR400 evolved 1.27 +/- 0.09 and 1.38 +/- 0.05 ml H2 mg dry wt(-1) l culture(-1), respectively over 10 h. This work provides the choice for using a recombinant E. coli strain, which produces H2 from sucrose, as an alternative to coupling-in an upstream invertase, and hence this provides a simpler method for the bioproduction of H2 from sucrose.

North Hammersmith stroke prevention project.

The North Hammersmith stroke prevention project was designed to reduce the number of deaths from stroke in this health district by improving the detection of hypertensive patients and thereafter reducing the default rate from treatment. Starting in May 1979 general practitioners in the district were asked to register hypertensive patients over the age of 40 so that the proportion of such patients in each practice was known and could be compared with the average for all practices. This confidential information was fed back every year to the individual general practitioners so that they could assess their performance. Forty of 44 eligible general practitioners agreed to participate and 29 proceeded to register patients. Over a three year period 1006 patients were registered, representing 4.3% of the project population over the age of 40. Individual practice registration rates ranged from 1.1% to 9.1%. Sixty five per cent of the registered patients were women, 34% of all registrations were in the age group 60-69, 31% in the group 50-59, 12% in the group 40-49, and 23% in the group over 70. The average blood pressure before treatment was 190/111 mm Hg. After one and two years the patients were contacted or their notes examined to ensure that they still receiving treatment. Persistant default from treatment occurred in under 12% over the three year period.