Monday, May 5, 2008
7-33
Sustained H2 photoproduction by Chlamydomonas reinhardtii cells entrapped within thin alginate films
Sergey N. Kosourov and Michael Seibert. Chemical and Biosciences Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401
Sustained H2 gas photoproduction in green algal cultures can be obtained by their incubation in sulfur-depleted medium (Melis et al. 2000, Plant Physiol 122:127-136; Ghirardi et al. 2000, Trends Biotechnol 18:506-511). Under continuous illumination, sulfur deprivation causes the partial and reversible inactivation of photosynthetic O2 evolution in algal cells, resulting in the establishment of anaerobic conditions in closed photobioreactors. The establishment of anaerobiosis leads to the induction of [FeFe]-hydrogenases in cells and subsequent H2 evolution for several days. However, H2 photoproduction in suspension cultures exhibits low light conversion efficiency (0.24%, Ghirardi 2006, Indian J Biochem Biophys 43:201-210), and the system is difficult to scale up and maintain. These problems can be overcome by immobilizing the cells within thin polymeric films (Gosse et al. 2007, Biotechnol Progress 23:124-130). In the present study, we report on the successful immobilization of sulfur/phosphorus-deprived algae in thin (< 400 μm) alginate films. The alginate film with entrapped sulfur/phosphorus-deprived C. reinhardtii cells demonstrates (a) higher volumetric cell density (up to 2000 µg Chl per mL of matrix), (b) H2 photoproduction for more than 300 h with an average light conversion efficiency of above 1%, (c) higher specific rates (up to 12.5 µmol mg-1 Chl h-1) of H2 evolution, and (d) unexpectedly high resistance of the H2-photoproducing system to inactivation by atmospheric oxygen.
This work was sponsored by the Air Force Office of Scientific Research (SK, MS) and the NREL LDRD Program (MS).
This work was sponsored by the Air Force Office of Scientific Research (SK, MS) and the NREL LDRD Program (MS).
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See more of The 30th Symposium on Biotechnology for Fuels and Chemicals (May 4 -- 7, 2008)