Springer Online Journal Archives 1860-2000
Abstract This study reports physiological features of a N2-fixing cyanobacteriumAnabaena doliolum in response to metal mixtures. Exposure of the cyanobacterium to Cu, Ni and Fe individually, as well as in combinations (Cu + Ni, Cu + Fe, Ni + Fe), showed marked differences in growth inhibition, nutrient uptake (NH4 + and NO3 −), photosynthesis, ATP content, nitrate reductase, glutamine synthetase and urease activities. The response to metal combinations was also dependent upon the order in which the metals were added. The Cu-Ni combination resulted in synergistic interaction, in contrast to the antagonism of Cu-Fe and Ni-Fe. Pre-addition of Fe protected the cyanobacterium against Cu and Ni toxicity. Statistically significant (P 〈 0.005) inhibition of all the processes following metal supplementation was observed. This study suggests that carbon fixation is the most suitable variable for assessing heavy metal toxicity.
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