Effects of Acute Salinity Stress on the Histological and Bacterial Community Structure and Function in Intestine of Stichopus monotuberculatus

This study focused on <i>Stichopus monotuberculatus</i> and conducted stress experiments at salinity levels of 20‱ and 40‱. Intestinal histological changes and the structural characteristics of the intestinal flora of <i>S. monotuberculatus</i> under salinity stress were analyzed. The results show that acute salinity stress inflicts varying degrees of damage to the intestinal tissues of <i>S. monotuberculatus</i>. Salinity stress enhances the species diversity of intestinal flora in <i>S. monotuberculatus</i>. Eight phyla of bacteria are detected in the intestine of <i>S. monotuberculatus</i>. Dominant phyla include Proteobacteria, Firmicutes, and Actinobacteria. Furthermore, functional prediction reveals that acute salinity stress can significantly modify the abundance of pathways associated with nutrient and energy metabolism mediated by the intestinal flora of <i>S. monotuberculatus</i>. These results indicate that acute salinity stress induces pathological damage to the intestinal tissues of <i>S. monotuberculatus</i>, compromising the microbial habitat and leading to alterations in the intestinal flora composition. Additionally, <i>S. monotuberculatus</i> can mitigate salinity stress by adjusting the composition of its intestinal flora and the corresponding functional pathways.