GROWTH AND CAROTENOGENESIS IN 8 STRAINS OF DUNALIELLA-SALINA TEODORESCO FROM CHILE

A study was made of growth and carotenogenesis in eight strains of the green alga Dunaliella salina collected from salt ponds at Salar de Atacama (23-degrees 30' S; 68-degrees 15' W) and Antofagasta (23-degrees 39' S; 70-degrees 24' W), Chile and kept in unialgal cultures at the Laboratorio Cultivo de Algas, University of Concepcion. The algae were grown in Erdschreiber medium supplemented with 12.5% w/v NaCl, under a continuous photon flux density of approximately 150-mu-mol-2 s-1 at 25 +/- 4-degrees-C without aeration. When growth reached the stationary phase, the amount of NaCl was increased to 25%. Total carotenoid content was measured during the exponential growth phase and 20 days after the addition of salt. Strain CONC-001 (Laguna La Rinconada, Antofagasta) exhibited the highest growth rate (k = 0.32 div d-1) and the lowest total carotenoid content (7.2 and 13.7 mg l-1 at 12.5 and 25% NaCl, respectively). Strain CONC-007 (Salar de Atacama) had the lowest growth rate (k = 0.14 div d-1) and yielded the highest total carotenes per volume unit (23.1 and 35.6 mg l-1 at 12.5 and 25% NaCl) and per cell (ca. 42 pg at 25% NaCl). Total carotenoid synthesis did not increase in strains CONC-001 and CONC-006 with the increase of salinity. These strains had the greatest increase of total carotenoid-to-chlorophyll ratio (4.5- and 9.3-fold, respectively). The seven strains from Salar de Atacama had higher total carotenoid contents than the strain from Antofagasta. Cell size also varied. Strain CONC-001 cells were smallest; strain CONC-006 had the largest cells. There was an inverse correlation between maximum cell density and mean cell size.