HALOTOLERANCE STUDIES ON CHLAMYDOMONAS-REINHARDTII - GLYCEROL EXCRETION BY FREE AND IMMOBILIZED CELLS

The freshwater green alga Chlamydomonas reinhardtii can tolerate a max imum saline concentration of 200 mM NaCl. In response to this osmotic shock, the cells accumulated during the first 24 h 15% of the total gl ycerol synthesized as osmoregulatory metabolite, to provide the corres ponding osmotic balance. After this period all glycerol synthesized wa s excreted to the medium, 4 g L-1 at 120 h in optimal conditions, befo re cell degradation occurred. This excretion was about 2-fold higher i n Ca-alginate entrapped cells in the presence of 250 mM NaCl. It was c oncluded that immobilized cells may be of biotechnological interest fo r continuous glycerol photoproduction in air-lift bioreactors.