Dietary Saccharomyces cerevisiae mitigates glyphosate-induced oxidative stress, immunotoxicity and apoptosis in Nile tilapia (Oreochromis niloticus)

Saccharomyces cerevisiae (SC) has emerged as a promising probiotic in aquafeeds for enhancing fish growth, health and resilience to environmental stressors. This study investigated the physiological, biochemical, histological and molecular effects of dietary SC supplementation in Nile tilapia (Oreochromis niloticus), under normal conditions and following glyphosate (GLY) challenge. Ninety fish (7.93 ± 0.026 g) were randomly allocated into two dietary groups (basal diet and basal diet supplemented with 4 g/kg SC) in triplicate for eight weeks. Following the feeding trial, each group was subdivided into unchallenged and GLY-challenged subgroups (0.6 mg/L; 3.55 μM). SC supplementation significantly improved final body weight, weight gain, specific growth rate and feed conversion ratio, accompanied by upregulation of hepatic insulin-like growth factor 1 (igf1) and downregulation of insulin-like growth factor-binding protein 1a (igfbp1a) and myostatin (mstn). GLY exposure induced hepatic and renal dysfunction, reflected by elevated serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea and creatinine, disrupted Lipid and protein profiles, and provoked oxidative stress, inflammation and apoptosis, evident by suppressed nuclear factor erythroid 2–related factor 2 (nrf2), superoxide dismutase (sod), lysozyme (lyz), and complement 3 (c3), alongside upregulation of kelch-like ECH-associated protein 1 (keap1), tumour necrosis factor-alpha (tnfα), cysteine-aspartic acid protease 3 (cas3) and cysteine-aspartic acid protease 9 (cas9). Histopathological examination confirmed GLY-induced damage in gills, liver and intestinal tissues. Notably, SC supplementation ameliorated these detrimental effects, preserving tissue integrity and restoring molecular and biochemical parameters. These findings highlight the potential of SC as a functional feed additive to enhance performance and mitigate glyphosate-induced toxicity in Nile tilapia, supporting sustainable and resilient aquaculture practices.