To investigate the protective effects of fish-derived Lactobacillus acidophilus AC on juvenile zebrafish (Danio rerio) under ammonia nitrogen stress, a total of 180 six-week-old AB strain juvenile Danio rerio mean weight (83.02±4.08) mg were randomly divided into four groups: AC0 group (0 CFU/mL Lactobacillus acidophilus AC), AC5 group (105 CFU/mL), AC6 group (106 CFU/mL), and AC7 group (107 CFU/mL). The bacteria were added to the rearing water for 32d, after which fish were exposed to 35.80 mg/L total ammonia nitrogen for 48h. The gill antioxidant parameters, gill tissue pathological changes, and the expression of related genes in gill and brain tissues were examined. Antioxidant parameters analysis of the gill tissues revealed that the activity of Na+/K+-ATPase and total superoxide dismutase (SOD) was significantly higher in the AC7 group than that in the AC0 (PPTNF-α) expression in AC7 significantly lower than that in the AC0 (PGDH) and SOD was significantly higher in AC7 than that in AC0 and AC5 (PGS) expression in both gill and brain was significantly higher in AC7 than that in the AC0 and AC5 (PBcl-2) expression in gill tissues was significantly upregulated in AC7 relative to other groups (Pcaspase 8 expression in gill and brain tissues was downregulated to varying degrees in all treated groups. In conclusion, Lactobacillus acidophilus AC alleviates oxidative stress damage in the gills by regulating the expression of antioxidant and ammonia assimilating enzyme genes, thus helping juvenile Danio rerio resist ammonia nitrogen stress.
XU et al. (2026) studied this question.