Immobilized bacterial consortium alleviates oxidative stress in juvenile African catfish (Clarias gariepinus) exposed to bisphenol-contaminated water

Health concerns about bisphenol A have prompted its replacement with analogues, bisphenol F (BPF) and bisphenol S (BPS). Regrettably, there is paucity of data on potential health hazards of these analogues while research on their removal from aqueous media is still emerging. In this study, effects of BPF and BPS exposure at sublethal concentration and bioremediation treatment were investigated on biochemical, hematological and histological parameters of selected organs (gills, liver, kidney, muscle and brain) of juvenile African catfish. 10% (10%) immobilized bisphenol-utilizing bacterial consortium was used for bioremediation treatment. Malondialdehyde (MDA) levels were assayed as an indicator of lipid peroxidation and oxidative stress. Activities of key antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx) and glutathione S transferase (GST), as well as concentration of non-enzymatic antioxidant reduced glutathione (GSH) were determined. Brain acetylcholinesterase (AChE) activity was evaluated as a biomarker of environmental stress. Histological analyses of selected fish tissues were conducted across all groups. Study was carried out in triplicates and results from treated groups were compared with those of the control group. Levels of malondialdehyde and glutathione peroxidase significantly increased in polluted groups while activities of superoxide dismutase, catalase, glutathione S transferase, acetylcholinesterase, and concentration of reduced glutathione significantly decreased in the pollution groups when compared with control. Remarkably, enzyme activities in treated groups were similar to results obtained in the control groups. Lesions observed in fish tissues of polluted group were minimal in treated groups. Hematological parameters which were significantly reduced in pollution group were elevated in treated groups. Findings provide evidence-based decisions for selecting immobilized microbes as bioremediation tools, and suggest the efficacy of bioremediation treatment in alleviating BPF and BPS toxicity in fish species.