EFFECTS OF LIGHT ON PIGMENTS AND PHOTOSYNTHETIC ACTIVITY IN A PHYCOERYTHRIN-RICH STRAIN OF SPIRULINA-SUBSALSA

Data on acclimation to 2 photon flux densities (15 and 100 mu mol phot ons m(-2) s(-1)) in Spirulina subsalsa strain 3F, a highly fluorescent phycoerythrin-rich cyanobacterium isolated from the brackish Lake Far e (Messina, Italy), indicated plasticity of the photosynthetic apparat us of this organism. High-irradiance grown cells showed the greatest p hotosynthetic capacity even though they had a lower chlorophyll and ph ycobiliprotein content. Carotenoids decreased to a lesser extent but t heir composition changed. beta-carotene decreased, while the amount of myxoxanthophyll more than doubled. The stability of both C-phycoeryth rin and C-phycocyanin ratios in cells grown under different light qual ity (green and red) demonstrated the lack of complementary chromatic a daptation in S. subsalsa. This factor, combined with the efficient uti lization of low-wavelength light, indicates the strong adaptation of t his strain to its habitat.