Effect of heavy metals (cadmium and lead) on growth, photosynthetic pigment content and Protein microalgae Isochrysis galbana

Heavy metals are especially important because of the toxic effects of the environment, the accumulation of biodiversity in various aquatic species and the creation of biological magnification in food chains. The present study was conducted to compare the toxicity of heavy metals of cadmium and lead in different concentrations (500, 250, 100, 50, 5 μg/L) on microorganism growth of Isochrysis galbana during 15 days in F2 culture media. The results showed that the effect of two metals on growth of I. galbana was dependent on two factors of time and concentration. Observations showed that concentrations of 500 micrograms per liter of cadmium on day 4 significantly inhibited the growth of I. galbana. The highest growth rate was obtained at a concentration of 5 μg/L for both tested metals. In this experiment, the highest content of chlorophyll a for cadmium and lead was 5 g/L and the lowest content of chlorophyll was in two concentrations of 250 and 500 μg/L. Also, by studying the effect of cadmium and lead on the amount of alfalfa protein, low concentrations increased protein levels and high concentrations reduced the amount of microalgae protein.