Cadmium- and chromium-induced damage and acclimation mechanisms in Scenedesmus quadricauda and Chlorella sorokiniana
2022
Volgusheva, A. | Todorenko, D. | Baizhumanov, A. | Chivkunova, O. | Solovchenko, A. | Antal, T.
In the present study, complex patterns of algal response to chromium (K₂Cr₂O₇, Cr) and cadmium (CdSO₄, Cd) toxicity were examined. Chlorophyll and starch content, photosynthetic activity and respiration rate, fatty acid content and composition, cell density (growth rate), malondialdehyde content (oxidative stress), ferric reducing antioxidant power and phenolic content (antioxidant activity) were measured in the model green algae species Scenedesmus quadricauda and Chlorella sorokiniana during exposure to 20 or 50 μM of Cr or Cd. Cell response to Cd showed similar patterns in both algae, whereas Cr effects differed, especially regarding the antioxidant activity. Malondialdehyde content, starch content, and respiration rate were the parameters most affected by both metals in both species. Only respiration rate increased dramatically under all treatments studied. In general, the Cd or Cr poisoning induced the transition of cell metabolism from “assimilatory” mode with active photosynthesis to “catabolic” mode characterized by elevated respiration and increased content of starch, a substrate for respiration. Chlorella sorokiniana cells showed a prominent response to Cr indicating suitability for bioassay of Cr contamination in the aquatic environment. A method for comprehensive screening of algal species on their heavy metal tolerance is proposed.
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