This study was to evaluate the growth, intestinal morphology, intestinal flora, and anti-infection activity against Aeromonas hydrophila in common carp upon adding Bacillus licheniformis to the feed. Four experimental diets supplemented with different concentrations of B. licheniformis were as follows: 0 (CK), 10⁶ colony forming units (CFU)/g (A), 10⁷ CFU/g (B), and 10⁸ CFU/g (C). After 60 days of feeding trial, the fish were intraperitoneally injected with 100 μL of A. hydrophila (LD₅₀=5×10⁶ CFU/mL) every day for a week to measure cytokines. Fish in group C showed the best growth indexes (weight gain rate: 186.88; specific growth rate: 1.76; and feed conversion rate: 1.07). The final body weight, weight gain rate, and specific growth rate in group C were increased by 47.9%, 87.4%, and 53.0%, feed conversion ratio reduced by 42.5%. Fish showed the highest villus height of intestine in group C. The intestinal flora analysis showed that, the richness of phylum, Firmicutes in the treatment groups significantly increased, and that of Bacteroides decreased remarkably. After the infection with A. hydrophila, B. licheniformis at 10⁸ CFU/g significantly upregulated protein levels of pro-inflammatory cytokines (TNF-α, IL-6) and anti-inflammatory cytokines (IL-10, TGF-β) compared with the control group. These results indicated that dietary supplementation of B. licheniformis not only increased the growth and influenced the intestinal development and disease resistance of common carp, but also altered the intestine microbiota structure. Furthermore, in our study, the optimal concentration of B. licheniformis in diets for common carp was equal to 10⁸ CFU/g.

这项研究旨在评估在饲料中添加地衣芽孢杆菌后，鲤鱼的生长，肠道形态，肠道菌群和对嗜水气单胞菌的抗感染活性。四种补充不同浓度地衣芽孢杆菌的实验饮食如下：0（CK），10 ^6个菌落形成单位（CFU）/ g（A），10 ⁷ CFU / g（B）和10 ⁸ CFU / g（ C）。投喂60天后，向鱼腹膜内注射100μL嗜水链球菌（LD ₅₀ = 5×10 ⁶CFU / mL），每周一次以测量细胞因子。C组鱼的生长指数最佳（增重率：186.88；比生长率：1.76；饲料转化率：1.07）。C组的最终体重，增重率和比生长率分别提高了47.9％，87.4％和53.0％，饲料转化率降低了42.5％。鱼在C组中显示出最高的肠绒毛高度。肠道菌群分析表明，治疗组中门，硬毛的丰富度显着增加，而拟杆菌的丰富度则显着降低。感染亲水性链球菌后，地衣芽孢杆菌在10 ⁸与对照组相比，CFU / g显着上调了促炎细胞因子（TNF-α，IL-6）和抗炎细胞因子（IL-10，TGF-β）的蛋白质水平。这些结果表明，膳食补充地衣芽孢杆菌不仅增加了鲤鱼的生长并影响了其鲤的肠道发育和抗病能力，而且还改变了其肠道菌群的结构。此外，在我们的研究中，鲤鱼饮食中地衣芽孢杆菌的最佳浓度等于10 ⁸ CFU / g。