Effects of Copper Ion (Cu 2+ ) on the Physiological and Biochemical Activities of the Cyanobacterium Nostoc ANTH

The effects of copper sulphate on the cyanobacterium Nostoc ANTH were studied. The copper concentrations chosen for the study were 0.5, 1.0, and 5.0 mg/L. From the results, it was observed that removal of Cu2+ ions by the organism was dependent on the external concentrations of Cu 2+ ions. Exposure to high concentrations of copper led to severe morphological changes in the cells, which were visible under transmission electron microscopy. Yet, complete elimination of copper from the growth medium led to poor growth, and ultimately the death, of the Nostoc ANTH cells. Cells exposed to low copper concentration (0.5 mg/L) in the medium showed comparable physiological and biochemical activities (such as growth, heterocyst frequency, nitrogenase activity, photosynthesis, and respiration) to that of the controlled cultures. However, these features were compromised as the copper concentration increased in the surrounding.