Halotolerance studies onChlamydomonas reinhardtii: glycerol excretion by free and immobilized cells

The freshwater green algaChlamydomonas reinhardtii can tolerate a maximum saline concentration of 200 mM NaCl. In response to this osmotic shock, the cells accumulated during the first 24 h 15% of the total glycerol synthesized as osmoregulatory metabolite, to provide the corresponding osmotic balance. After this period all glycerol synthesized was excreted to the medium, 4 g L^-1 at 120 h in optimal conditions, before cell degradation occurred. This excretion was about 2-fold higher in Ca-alginate entrapped cells in the presence of 250 mM NaCl. It was concluded that immobilized cells may be of biotechnological interest for continuous glycerol photoproduction in air-lift bioreactors.