Intestinal microbiota of fish plays critical roles in growth and development, nutrient absorption, immune regulation, and other aspects. Therefore, revealing the dynamic succession patterns and colonization mechanisms of the intestinal microbial composition in Huso dauricus provides the theoretical foundation for regulating sturgeon growth and development.
This study aimed to investigate the characteristics of the microbial communities in the intestine of Huso dauricus larvae, food, and water to identify the factors influencing intestinal microbiota colonization of sturgeon. Samples were collected from 36 Huso dauricus larvae. DNA samples were extracted from intestinal contents, food sources, and water, followed by 16S rRNA gene sequencing at the key developmental stages: 7 days (benthic stage), 14 days (fed with chironomid larvae), 23 days (fed with a mixture of chironomid larvae and formulated feed), and 41 days (fed with formulated feed). Results revealed that at the genus level, the predominant bacterial taxa in the intestinal microbiota, chironomid larvae, and feed was Pseudomonas, while the dominant bactreia flora in water was Clostridium. After feeding with chironomid larvae, the intestinal microbiota was gradually similar with chironomid larvae, indicating that food primarily influences the structure and composition of the intestinal microbiota in sturgeon. Furthermore, KEGG pathway enrichment analysis showed that the relative abundances of the "Biosynthesis of amino acids" and "Microbial metabolism in diverse environments" pathways decreased from days 14-23 compared to day 7, and reached to the peak at day 41, and showed no significant difference between day 41 and day 7. Our study demonstrated that Huso dauricus larvae could adapt to the external environment during the growth and development stage through the dynamic changes in the metabolism functions of gut microbe community.

Huso dauricus; Microbial community succession; gut microbe; aquaculture