THE MICROALGA CHLAMYDOMONAS-REINHARDTII CW-15 AS A SOLAR-CELL FOR HYDROGEN-PEROXIDE PHOTOPRODUCTION - COMPARISON BETWEEN FREE AND IMMOBILIZED CELLS AND THYLAKOIDS FOR ENERGY-CONVERSION EFFICIENCY

Immobilized cells and thylakoid vesicles of the microalga Chlamydomona s reinhardtii CW-15 have been developed as a solar cell because of the ir capabilities of producing hydrogen peroxide. This compound is an ef ficient and clean fuel used for rocket propulsion, motors and for heat ing. Hydrogen peroxide is produced by the photosystem in a catalyst cy cle in which a redox mediator (methyl viologen) is reduced by electron s obtained from water by the photosynthetic apparatus of the microalga and it is re-oxidized by the oxygen dissolved in the solution. The ph otoproduction has been investigated using a discontinuous system with whole cells, or thylakoid vesicles, free or immobilized on alginate. T he stimulation by azide as an inhibitor of catalase has also been anal yzed. Under determined optimum conditions, the photoproduction by Ca-a lginate entrapped cells, with a rate of 33 mu mol H2O2/g Chl.h, was ma intained for several hours with an energy conversion efficiency of 0.2 5%.