Biochemical, histological, and molecular investigation of fish exposed to a brewery effluent

Abstract Background Breweries' industrial processes produce much effluent, which, if improperly managed, could contaminate the aquatic bodies that receive them. The effect of brewery effluent on fish health was investigated to assess the extent of pollution on the fish population. Samples of Clarias gariepinus L were exposed to varying concentrations of brewery effluent. After exposure, key biochemical indicators of oxidative stress response were analyzed. Messenger RNA expressions of genes associated with growth, reproduction, oxidative stress, and toxicity were quantified. The histopathological architecture of the liver was also examined. Results Exposure of fish to the brewery effluent increased conjugated diene and malondialdehyde levels, while the activity of antioxidant enzymes (catalase and SOD) significantly ( p < 0.05) decreased relative to control fish. The effluent increased the mRNA expression of growth hormones (GHs), CAMKIIg, MEL1C, IL-1β, CYP11A, HSP70, and DMRT1, while decreasing the expression of HSD17B and FOXL2 when compared to control fish ( p < 0.05). The histological study revealed liver degeneration from the normal architectural structure with simple steatosis and structurally enlarged central vein coupled with Mallory bodies. Conclusion The results indicate that effluent discharge from the brewery industry can harm fish population by altering antioxidant enzymes and expression of growth hormones. Hence, prior discharge into water bodies, industrial effluents should be effectively treated to meet standards and guidelines stipulated by environmental regulatory bodies.