Probiotic (Bacillus cereus) enhanced growth of Pengze crucian carp concurrent with modulating the antioxidant defense response and exerting beneficial impacts on inflammatory response via Nrf2 activation

摘要

The purpose of this research was to explore the mechanism of action of B. cereus on Pengze crucian carp (Carassius auratus var. Pengze). Fish fed basal diet with supplementation of living (LBC group) and heated-inactivated (HIBC group) B. cereus at the dose of 1 x 10(9) CFU kg(-1), and basal diet served as Control group. Our results indicated that both additives remarkably promoted the growth of fish (P < .05). Compared to Control group, living B. cereus significantly improved serum antioxidant status through an elevation in the activities of total superoxide dismutase, catalase and glutathione peroxidase and the concentration of reduce glutathione (P < .05), whereas only a significantly higher catalase activity was detected in fish fed heated-inactivated B. cereus (P < .05), concurrent with a significant decrease in malondialdehyde concentration in two additive groups (P < .05). Meanwhile, the intestinal antioxidant property was improved in two additive groups through the increase in catalase and glutathione peroxidase activities and reduce glutathione content together with a significantly lower malondialdehyde content (P < .05). The gene expression analysis indicated that the improvement of intestinal antioxidant property appeared to be associated with Nrf2 signaling pathway via upregulating the mRNA levels of target genes like catalase, glutathione peroxidase 1, or copper/zinc superoxide dismutase. Besides, living and heated-inactivated B. cereus supplementation could inhibit intestinal inflammatory responses by suppressing the transcription of pro-inflammatory cytokine due to the regulation of antioxidant system by Nrf2 activation and inducing the overexpression of anti-inflammatory cytokine interleukin-10 (P < .05). Then, the intestinal barrier function in two B. cereus groups was improved by up-regulating expression of tight junction protein genes like Claudin12, zonula occludens 1, and/or Occludin-like (P < .05). These results revealed that probiotics B. cereus supplementation could promote the growth and further improve intestinal health by enhancing antioxidant capacity, suppressing inflammatory response, and improving intestinal barrier function of Pengze crucian carp through Nrf2 signaling pathway.