Potential of microalgae Parachlorella kessleri Bh-2 as bioremediation agent of heavy metals cadmium and chromium

Abstract

The basis of biological remediation basically refers to environmentally friendly methods of extracting various xenobiotics, including heavy metals, from the wastewater of various industrial facilities, using the biochemical capabilities of naturally occurring organisms or their metabolites. In this regard, the assessment of the contribution of microalgae to the transformation of heavy metal compounds and the detoxification of the natural environment is very important and necessary. This paper presents an investigation of the effect of different concentrations of cadmium Cd2+ and chromium Cr2O72− ions on the survival and ultrastructure of microalgae cells of Parachlorella kessleri Bh-2 and its ability to accumulate these metals in order to determine its bioremediational potential against these metals. It was determined that the culture of Parachlorella kessleri Bh-2 is resistant to concentrations of cadmium (0.3 mg l−1) and chromium (30 mg l−1) ions. It was found that heavy metals in these concentrations are actively transported through the cell membrane and accumulate in the cytoplasm of cells, causing an increase in the number of vacuoles with electron-dense deposits, granulation of the cytoplasm and an increase in the number of starch grains in the microalgae cells. Analysis of the content of total polysaccharides showed a noticeable increase in the concentration of polysaccharides by of exposure to concentrations of Cd (II) - 0,3 mg l−1 and Cr (VI) - 30 mg l−1.