Sun Hang, Wang Luxi, Chen Fangyi, Meng Xiangyu, Zheng Wenbin, Peng Hui, Hao Hua, Chen Huiyun, Wang Ke-Jian
State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiang'an South Road, Xiamen, 361102, Fujian, China.
Department of Physiology, School of Basic Medical Sciences, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Anim Microbiome. 2024 Oct 8;6(1):54. doi: 10.1186/s42523-024-00342-3.
Our previous study revealed that feeding the antimicrobial peptide (AMP) product Scy-hepc significantly enhances the growth of mariculture fish through the activation of the GH-Jak2-STAT5-IGF1 axis. However, the contribution of gut microbiota to this growth enhancement remains unclear. This study aimed to elucidate the potential mechanism involved in intestinal absorption and modulation of gut microbiota in Epinephelus akaara following Scy-hepc feeding.
The results showed that a 35 day regimen of Scy-hpec markedly promoted the growth of E. akaara compared to groups supplemented with either florfenicol, B. subtilis, or a vector. The growth enhancement is likely attributed to alterations in microbiota colonization in the foregut and midgut, characterized by an increasing abundance of potential probiotics (Rhizobiaceae and Lysobacter) and a decreased abundance of opportunistic pathogens (Psychrobacter and Brevundimonas) as determined by 16S rRNA analysis. Additionally, similar to the effect of florfenicol feeding, Scy-hepc significantly improved host survival rate by over 20% in response to a lethal dose challenge with Edwardsiella tarda. Further investigations demonstrated that Scy-hepc is absorbed by the fish foregut (20-40 min) and midgut (20-30 min) as confirmed by Western blot, ELISA, and Immunofluorescence. The absorption of Scy-hepc affected the swimming, swarming and surfing motility of Vibrio harveyi and Bacillus thuringiensis isolated from E. akaara's gut. Moreover, Scy-hepc induced the downregulation of 40 assembly genes and the upregulation expression of 5, with the most significant divergence in gene expression between opportunistic pathogens and probiotics concentrated in their motility genes (PomA/B, MotA/B).
In summary, this study shows that feeding AMP Scy-hepc can promote growth and bolster immunity in E. akaara. These beneficial effects are likely due to the absorption of Scy-hepc in the fish's foregut and midgut, which modulates the colonization and motility of commensal bacteria, leading to favorable changes in the composition of the foregut and midgut microbiota. Therefore, a profound understanding of the mechanisms by which antimicrobial peptides affect host gut microbiota will contribute to a comprehensive assessment of their advantages and potential application prospects as substitutes for antibiotics in fish health and improving aquaculture practices.
我们之前的研究表明，投喂抗菌肽（AMP）产品Scy-hepc可通过激活GH-Jak2-STAT5-IGF1轴显著促进海水养殖鱼类的生长。然而，肠道微生物群对这种生长促进作用的贡献仍不清楚。本研究旨在阐明投喂Scy-hepc后，赤点石斑鱼肠道吸收及肠道微生物群调节的潜在机制。
结果显示，与投喂氟苯尼考、枯草芽孢杆菌或载体的组相比，35天的Scy-hpec投喂方案显著促进了赤点石斑鱼的生长。生长促进可能归因于前肠和中肠微生物群定植的改变，通过16S rRNA分析确定，其特征是潜在益生菌（根瘤菌科和溶杆菌属）丰度增加，机会致病菌（嗜冷杆菌属和短波单胞菌属）丰度降低。此外，与投喂氟苯尼考的效果类似，Scy-hepc在迟缓爱德华氏菌致死剂量攻击下，显著提高了宿主存活率超过20%。进一步研究表明，通过蛋白质免疫印迹、酶联免疫吸附测定和免疫荧光证实，Scy-hepc被鱼的前肠（20 - 40分钟）和中肠（20 - 30分钟）吸收。Scy-hepc的吸收影响了从赤点石斑鱼肠道分离的哈维氏弧菌和苏云金芽孢杆菌的游泳、群游和冲浪运动能力。此外，Scy-hepc诱导40个组装基因下调，5个上调表达，机会致病菌和益生菌之间基因表达的最大差异集中在其运动基因（PomA/B、MotA/B）上。
总之，本研究表明投喂AMP Scy-hepc可促进赤点石斑鱼生长并增强免疫力。这些有益作用可能是由于Scy-hepc在鱼的前肠和中肠吸收，调节共生细菌的定植和运动能力，导致前肠和中肠微生物群组成发生有利变化。因此，深入了解抗菌肽影响宿主肠道微生物群的机制，将有助于全面评估其作为鱼类健康中抗生素替代品的优势和潜在应用前景，并改善水产养殖实践。
