Selenium-enriched Bacillus subtilis attenuates emamectin benzoate-induced liver injury in grass carp through inhibiting inflammation and ferroptosis via activating Nrf2 signaling pathway.

The widespread use of emamectin benzoate (EMB) has caused many pests to develop resistance to it, and there have been reports of toxic effects of methomyl on marine animals. We tested whether Se-rich B. subtilis exerted protective effects against EMB-induced liver injury in grass carp. The carps were cultured in an aquatic environment containing 2.4 μg/L of EMB for 30 days. Se-rich B. subtilis (105, 106, 107 Colony Forming Unit (CFU)/g) was given daily for 10 days. According to the results, Se-rich B. subtilis alleviated liver pathological injury, aspartate aminotransferase (AST), alanine aminotransferase (ALT), TNF-α and IL-1β production. Meanwhile, EMB-induced ferroptosis was attenuated by Se-rich B. subtilis. The subsequent experiment revealed that Se-rich B. subtilis inhibited EMB-induced nuclear factor kappa-B (NF-κB) activation. Further research demonstrated that nuclear factor erythroid-2 related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) expression was increased by Se-rich B. subtilis. Taken together, Se-rich B. subtilis attenuated EMB-induced liver injury by alleviating inflammation and ferroptosis via Nrf2 signaling.