Sunday, April 29, 2007

Nano-porous latex coatings containing Rhodopseudomonas palustris pigment mutants spatially distributed for hydrogen production

Jimmy L. Gosse1, Brian J. Engel1, Federico E. Rey2, Caroline S. Harwood2, and Michael C. Flickinger3. (1) Department of Biochemistry, Molecular Biology & Biophysics, BioTechnology Institute, University of Minnesota, 1479 Gortner Ave., St. Paul, MN 55108, (2) Department of Microbiology, University of Washington, Box 357242, Seattle, WA 98195, (3) Microbiology; Chemcial and Biomolecular Engineering; BTEC, North Carolina State University, Centennial Campus, Campus Box 7928, Raleigh, NC 27695

The hydrogen production rate from <70 μm thick latex coatings containing non-growing Rhodopseudomonas palustris CGA009 in the presence of acetate is stable for >2000 hours at 2 mmol H2 m-2 hr-1.  Although this rate is significant it can be further improved by altering the photosynthetic capacity of Rps. palustris and thereby optimizing the coating for light absorption. It has been demonstrated in suspension photobioreactors that reduced pigment mutants of photosynthetic organisms have higher hydrogen production rates than an equivalent density of wild type cells.  Immobilization of these mutants in latex may result in an increase in the specific activity of the cells. A multi-layer coating allows for combining strains in defined spatial arrangements for the optimal utilization of light.  Hydrogen production rates have been determined for monolayer latex coatings containing photosynthetic pigment mutants of Rps. palustris.  Composite coatings of mutants were evaluated to investigate the affect of spatial arrangement (uniform mono-layer, mixed mono-layer, and multi-layer coatings) on hydrogen production specific activity (H2 production rate / coating thickness).  Stable long term hydrogen production rates can be achieved for each system.