Evaluation of antioxidative response of diatoms grown on emerging steroidal contaminants

With increasing anthropic activities, a myriad of typical contaminants from industries, hospitals, and municipal discharges have been found which fail to be categorized under regulatory standards and are hence considered contaminants of ‘emerging concern’. Since these pollutants are not removed effectively even by the conventional treatment system, they tend to inflict potential threats to both humans as well as aquatic life. However, microalgae-mediated remediation strategies have recently gained worldwide importance owing to their role in carbon fixation, low operational cost, and production of high-value products. In this study, centric diatom Chaetoceros gracilis was exposed to different concentrations of estradiol (E2) induced synthetic media ranging from 0 to 2 mg L − 1 , and its impact on the antioxidative system of the algae was investigated. The results indicate that the nutrient stress caused an elevation in the antioxidative response of the diatom triggering the release of radical scavenging enzymes like catalase (CAT), and ascorbate peroxidase (APX) as well as superoxide dismutase (SOD). Maximum specific activity (U mg − 1 of protein) of CAT and APX was noted in the diatom culture supplemented with 0.5 mg L − 1 . However, peroxidation of lipid membranes was more intense in the setups with greater oxidative stress that the ones with higher E2 concentrations. Thus, the study reveals the scope of diatoms as potential indicators of environmental stress even under the varying concentration of a single contaminant (E2).