Improvement of intestinal barrier, immunity, and meat quality in common carp infected by Aeromonas hydrophila using probiotics

The fish pathogen Aeromonas hydrophila causes gastrointestinal tract infections and hemorrhagic septicemia and represents a widespread risk in aquaculture. This study aimed to determine whether compound probiotics could improve the intestinal barrier, immunity, and meat quality of common carp infected by A. hydrophila by feeding them compound probiotics. Carp were assigned to one of four groups: (1) control (no infection, no probiotics); (2) control + probiotic; (3) A. hydrophila infected; and (4) the A. hydrophila + probiotic group. At the beginning of the experiment, the carp were injected with either saline (0.86%) or A. hydrophila (4.87 x 10(7) CFU/mL). After 2 weeks of the feeding regime, results suggested that in A. hydrophila infected carp, dietary probiotics regulated the intestinal microflora as evidenced by a reduced abundance of Proteobacteria and increased amounts of Firmicutes and Fusobacteria in the intestine. In addition, dietary probiotics ameliorated both villus swelling and the decrease in villus height induced by A. hydrophila (P < 0.05). Moreover, probiotics prevented the A. hydrophila-induced decline of Occludin, Claudin-1, and ZO-1 levels in the intestine (P < 0.05). The addition of probiotics into the feed also increased acid phosphatase (ACP), alkaline phosphatase (AKP), and lysozyme (LZM) activity in the serum (P < 0.05), in comparison to the A. hydrophila group. Importantly, when compared to A. hydrophila-infected carp, compound probiotics alleviated the decrease in muscle nutrient quality (P < 0.05). In summary, we show that dietary compound probiotics can prevent the impact of A. hydrophila infection on the intestinal function and disease resistance, while ensuring carp muscle quality.

Automated summary

This study demonstrates that dietary compound probiotics can enhance intestinal function and disease resistance in common carp infected with A. hydrophila, while also preserving muscle quality.