EFFECT OF NUTRITIONAL REGIME ON ACCUMULATION OF COBALT, MANGANESE AND ZINC BY GREEN MICROALGAE

Accumulation of cobalt, manganese and zinc by the algae Chlorella emersonii, Chlamydomonas reinhardtii and Scenedesmus obliquus has been characterized under photoautotrophic, photoheterotrophic and chemoheterotrophic nutritional regimes. All three species accumulated smaller amounts of CO2+, Mn2+ and Zn2+ under chemoheterotrophic and photoheterotrophic conditions than under photoautotrophic conditions except in the case of cobalt accumulation by C reinhardtii where there was little difference in the amount of cobalt accumulated under any of the nutritional regimes. Decreased accumulation of the three metals by C emersonii and C reinhardtii largely resulted from a decrease in the initial biosorptive phase of uptake whereas the decrease in Mn2+ and Zn2+ accumulation by C reinhardtii under chemoheterotrophic and photoheterotrophic conditions was due to a decrease in the slow energy-dependent phase of uptake.