The effect of copper on the abundance, cell morphology and content of photosynthetic pigments in the microalga Porphyridium purpureum

Abstract

Red microalga Porphyridium purpureum adaptive abilities to copper intoxication were studied. Cell number dynamics and morphology, contents of chlorophyll a and carotenoids were used as test-points. The experiment was conducted in two stages. At the first stage the effect of copper in concentrations of 50 and 100 µg·l−1 was studied; at the second stage the alga adaptive abilities to growth in copper contaminated medium were assessed. At the first stage copper concentration of 50 µg·l−1 didn’t influence the parameters under study. Addition of 100 µg·l−1 caused growth inhibition and photosynthetic pigment content decrease. At the second stage after transferring alga to a medium with 50 µg·l−1 copper concentration from a medium with similar conditions, cell number and photosynthetic pigment content were not significantly different from the control ones. Part of the cells deformed, chloroplasts became darkened. Transferring to a medium with 100 µg·l−1 from a medium with 50 µg·l−1 copper concentration caused growth delay; most of the cells in suspension were with dark, granulated chloroplast. Cells transferring from a medium with 100 µg·l−1 to a medium with the same concentration resulted in growth inhibition and photosynthetic pigment content decrease. Part of the cells in suspension became lager than in control and with great amount of mucilage. Complete adaptation of P. purpureum to copper intoxication didn’t occur.