Effect of dietary Bifidobacterium animalis subsp. lactis BLa80 on growth, immune response, antioxidant capacity, and intestinal microbiota of juvenile Japanese seabass (Lateolabrax japonicus)

To evaluate the potential of Bifidobacterium animalis subsp. lactis BLa80 (BLa80) as a probiotic for Japanese seabass ( Lateolabrax japonicus ) aquaculture, we assessed the effects of BLa80 on the growth, immune response, antioxidant capacity, and intestinal microbiota of Japanese seabass. Fish fed normal feed (non-BLa80) or feed with 1×10 10 CFU/g BLa80 were cultured for 15 (15d-BLa80) or 30 (30d-BLa80) days in a recycling seawater system indoor. The results showed that BLa80 supplementation improved survival, increased body mass index, and accelerated the growth of juvenile Japanese seabass. BLa80 treatment decreased the levels of oxidants (H 2 O 2 and malondialdehyde) and increased the activities of antioxidants (catalase, glutathione peroxidase, glutathione S-transferase, serum superoxide dismutase, total antioxidant capacity, and glutathione). BLa80 reduced hindgut T-help 17 cell-related factors (IL-17, TNF-α, and RORγ) and increased regulatory T cell-related factors (IL-10 and Foxp3) comparing with control. BLa80 stimulated the hindgut anti-apoptotic gene Bcl-2 and downregulated the expression of pro-apoptotic genes ( JNK , FoxO3a , PUMA , Bax , Apaf-1 , Caspase-3 , and Caspase-9 ). These results indicate that BLa80 supplementation significantly promotes the growth, enhances serum antioxidant capacity, reduces apoptosis of the hindgut and liver cells, improves innate immunity of the hindgut, and alters the structure of the hindgut microbiota of juvenile Japanese seabass.