IMMOBILIZED CELLS OF A UNICELLULAR GREEN-ALGA AND A PHOTOSYNTHETIC BACTERIUM FOR USE IN A BIOPHOTOLYSIS SYSTEM

Immobilization of algal and bacterial cells was investigated, and found applicable to our hydrogen production system. Both a unicellular green alga, Chlamydomonas reinhardtii, and a photosynthetic bacterium, Rhodospirillum rubrum, were separately entrapped in calcium alginate gel. The photosynthetic starch accumulation and subsequent dark fermentation of C. reinhardtii were not affected by cell immobilization in Ca-alginate gel. Immobilized cells of R. rubrum retained their ability to utilize various electron donors for hydrogen evolution. Immobilized R. rubrum was stable, at least for a week, in a light and dark cycle. These and other observations suggest that the immobilization of cells could facilitate the broth-recycle between an algal culture system and a bacterial hydrogen production unit.