Responses of cyanobacterium Anabaena doliolum during nickel stress

Growth and biochemical responses of heterocystous nitrogen fixing cyanobacteria Anabaena doliolum were studied upon exposure to various concentrations of nickel (0.1 to 100 mu M) for duration of upto 4 days, in view of its tolerance. The growth of the cyanobacterium was increased in terms of cell density (O.D), heterocyst frequency, chlorophyll-a, carotenoid and c-phycocynin upto moderate exposure (10 mu M for 96 hr of Ni treatment). Protein and total non protein thiol were measured as stress responsive metabolites and frequency of heterocyst and spores were observed in responses to Ni. The present study demonstrated that the tested cyanobacterium exhibited dose specific responses of metal towards studied different morphological, physiological and biochemical parameters.