Aquaculture Reports (Feb 2022)
Dietary quenching enzyme AiiO-AIO6 promotes fish growth through intestinal microbiota: Zebrafish as a model
Abstract
The growth performance of cultured aquatic animals is directly related to the economic benefit of the aquaculture industry. Quenching enzyme AiiO-AIO6 could degrade quorum sensing signal molecules N-acylhomoserine lactone (AHL), in this work, the effects of this AiiO-AIO6 on the growth of zebrafish was studied, the control group and AiiO-AIO6 additive group were set up with 120 fish in each group, and the feeding experiment was carried out for three weeks. The following results were obtained by observation of intestinal structure and morphology, quantitative PCR, gut microbes sequencing analysis and transfer, etc. The results showed that the final weight, weight gain rate and specific growth rate were significantly increased and feed conversion ratio and feeding rate of AiiO-AIO6 treated group were significantly decreased. Intestinal digestive enzyme assay showed that there was no significant difference in amylase, lipase and protease activities between the AiiO-AIO6 and control group. Hematoxylin and eosin (H&E) staining of intestinal morphology showed that the height of villus, the number of goblet cells and the height of columnar epithelial cells were significantly increased in the AiiO-AIO6 group. In addition, the relative expression levels of intestinal nutrient transporters Pept1a, GLUT2 and FATP1-a were also significantly increased. The analysis of intestinal microbiota structure and short-chain fatty acids showed that the addition of AiiO-AIO6 could change intestinal microbiota structure and increase the contents of acetic acid and isovalerate. The expression of growth-related genes in intestine, liver and muscle of two groups showed that growth hormone GH, GH receptor GHra, insulin-like growth factor IGF-I and myogenic factor Myf5 of AiiO-AIO6 group were significantly up-regulated. Results in the germ-free zebrafish model showed that the expression of growth-related genes was not directly regulated by AiiO-AIO6, but was mediated by the action of active intestinal microbiota. Overall, our data reflected that AiiO-AIO6 can promote the growth performance of zebrafish, and AiiO-AIO6 is a potential functional additive to make aquaculture efficient and high-yielding.
