engleski

Algal cells under heavy metal stress: physiological and morphological response

Heavy metals can cause diverse negative impacts on marine ecosystems including impact on the major primary producer and the base of the food web – algae. The impact of cadmium on lightly silicified marine diatom Cylindrotheca closterium was studied. C. closterium cultures were exposed to 0-1000 µg L-1 Cd and growth dynamics was followed with optical microscope using haemocytometer. The increased cadmium concentrations form 1 to 1000 µg L-1 in C. closterium cultures induced decrease of specific growth rates in exponential growth phase. Morphological changes on the cell surface of C. closterium exposed to cadmium were characterized at the nanoscale using atomic force microscope (AFM). The morphological changes were observed as irregular patterns of silica spheres on more silicified parts of the cell, girdle band and around the raphe of the cells that grew at 1000 µg L-1. Cadmium uptake clearly affected the biosilica formation mechanism in C. closterium, most probably by interfering in biological and physicochemical processes involved in diatom biosilification.

algal cells ; heavy metal

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