Amelioration of Cd-induced bioaccumulation, oxidative stress and intestinal microbiota by Bacillus cereus in Carassius auratus gibelio.

The heavy metal cadmium (Cd) is a hazardous pollutant known to exert various toxic effects and other sublethal to lethal effects on aquatic organisms, and can be commonly found in environment. The genus Bacillus was one of dominant probiotics, which was commonly used in aquaculture. The aim of this study was to evaluate the effects of dietary administration of Bacillus cereus (B. cereus) on bioaccumulation, oxidative stress and intestinal microbiota of Carassius auratus gibelio (C. gibelio) after Cd exposure. Fish were exposed for 4 weeks to waterborne Cd at 0, 1 and 2 mg/L and/or dietary B. cereus at 10⁸ cfu/g. At 2 and 4 weeks, the fish were sampled and bioaccumulation, antioxidant activity and intestinal microbiota were assessed. Waterborne Cd exposure caused marked alterations in the composition of the microbiota. Dietary supplementation with B. cereus can reverse the changes in the composition of intestinal microbiota in Cd exposure and increase the abundance of Bacteroides, Akkermansia, Cetobacterium in the 0 and 1 mg/L Cd. The results obtained indicate that B. cereus can provide a significant protective effect on the toxicity of cadmium by inhibiting alterations in the levels of bioaccumulation and antioxidant enzyme including Superoxide dismutase (SOD), catalase (CAT), total antioxidant (T-AOC), glutathione (GSH), malonaldehyde (MDA) and Glutathione-S-transferase (GST). The present findings imply that dietary supplement of B. cereus can effectively protect C.gibelio to combat cadmium toxicity.