The effects of different concentrations of lead on the growth, photosynthetic pigments and malondialdehyde content of the unicellular green algae Chlorella Vulgaris

Lead as a contaminant of the environment cause cell poisoning. The unicellular green algae Chlorella Vulgaris belongs to the family Chlorellaceae. Since C.Vulgaris has a simple cell structure and unique feature, it is used as a model in plant physiological studies. In order to investigate the growth and adaption of Chlorella sp. to different concentrations of lead (0,10 ,50 , 80 mgL-1) , an experiment was done in the medium Zn With 3 replication in the growth chamber with 12 h light photoperiod, temperature of 25 ± 2 °C, light intensity of 2500 lux and with proper aeration, during 18 days. Growth curve of total samples were determined by measuring the absorbance of 750 nm. Growth rate, chlorophylls and malondialdehyde content and sorption of lead by the algae were measured. Results showed that by increasing concentrations of Lead in the medium up to 80 mgL-1, biomass production, photosynthetic pigments and subsequent growth rate were decreased and samples in less time were able to enter stationary phase and the amount of malondialdehyde (MAD) in treatment of 50 and 80 mgL-1 were significantly increased compared to control. Generally, high concentrations of toxic metal lead influenced the majority of physiological and vital parameters of C.Vulgaris but as a resistant microalgae, despite of the reduction in cell division still retained its growth potential.