Effect of Copper and Lead on Growth and Some Metabolic Activities of Cyanobacterium Spirulina platensis (Nordstedt)

Abstract

TODAY the heavy metal pollution is one of the most important environmental problem, which causes in soil and aquatic environment. Biosorption is an innovative technology that employs biological materials to accumulate heavy metals from waste water through metabolic process or physicochemical pathways of uptake. We studied the metabolic responses of Spirulina platensis to the toxicity of two heavy metals,Cu2+ and Pb2+. The data show that the lower doses of metals had stimulatory effect on biomass of Spirulina platensis, whereas the higher doses were found to be inhibitory depending on the type of the metal. The inhibitory effect of copper upon growth parameters of Spirulina platensis was more pronounced than lead. The total protein content, chlorophyll content, total carbohydrate and the total free amino acids of the tested alga gradually decreased in a manner dependent on the metal concentration in the medium. Biosorption of algal biomass was found to be heavy metal concentrations and pH dependent, where Spirulina platensis accumulated the amount of Pb2+ more than Cu2+. Concerning the effect of different concentrations of Cu2+ and Pb2+ on photosynthetic O2 evolution, the results showed reduction in the amount of O2 evolved in response to increasing metals concentrations. On the other hand, the effect of the heavy metals on respiration showed that higher metals concentrations were inhibitory to O2 uptake by Spirulina platensis.