Effects of Bacillus coagulans on the cadmium content, antioxidant capacity and inflammatory response in the liver of Cyprinus carpio under cadmium exposure

Cadmium (Cd) is one of the heavy metal contamination sources and can be released into the aquatic environment through agriculture, industry and other human activities. In most contaminated aquatic environments, the fish are often threatened by excessive accumulation of Cd, which may cause oxidative stress, immune damage, growth inhibition and even death of fish. In addition, Cd exposure can promote the metal bioaccumulation in fish, thereby continuously affecting human health through the food chain. Thus, identifying a safe and effective natural substance against Cd toxicity is of great importance for the effective management of aquatic animal health and alleviaton of the pressure on food safety. The use of probiotics to protect the humam body from the toxicity of heavy metals has become a hot research topic in recent years. The purpose of this test is to explore the effects of Bacillus coagulans SCC-19 on the cadmium content, antioxidant capacity and inflammatory response in the liver of Cyprinus carpio under cadmium exposure. The 450 C. carpio with an average weight of (34.00±1.16 g) were selected and randomly divided into 5 groups (control group, 0.5 mg/L Cd²⁺ group, 0.5 mg/L Cd²⁺+10⁷ CFU/g B. coagulans group, 0.5 mg/L Cd²⁺+10⁸ CFU/g B. coagulans group and 0.5 mg/L Cd²⁺+10⁹ CFU/g B. coagulans group), with 3 replicates in each group and 30 fish in each replicate. The results indicated that compared with the cadmium exposure group, B. coagulans SCC-19 could effectively reduce the cadmium content in the liver of C. carpio, and reduce the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, and significantly increase the level of metallothionein (MT) in the liver of C. carpio. In addition, the total antioxidant capacity (T-AOC), anti-superoxide anion free radical activity (ASA) and anti-free radical hydroxyl ability (AHA) of in the liver of C. carpio in the B. coagulans SCC-19 groups were significantly higher than the those in control group, while the levels of reactive oxygen species (ROS), malonaldehyde (MDA) and hydrogen peroxide (H₂O₂) in the B. coagulans SCC-19 groups were significantly lower than those in the control group. Moreover, the results showed that B. coagulans SCC-19 could alleviate the genes of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and transforming growth factor-β (TGF-β) abnormal expression. The results of the study show that B. coagulans SCC-19 can reduce the cadmium content, relieve oxidative stress, and inhibit inflammation in the liver of C. carpio under cadmium exposure.