The Damage of the Crayfish (Procambarus Clarkii) Digestive Organs Caused by Citrobacter Freundii Is Associated With the Disturbance of Intestinal Microbiota and Disruption of Intestinal-Liver Axis Homeostasis

Abstract

As a common conditional pathogenic bacterium in nature, <i>C. freundii</i> has posed a threat to crayfish culture and may infect humans through consumption. However, the pathogenic mechanism of <i>C. freundii</i> in crayfish remains unknown, which poses difficulties for the prevention and control of the bacterium. In this study, the effects of <i>C. freundii</i> on the digestive organs, intestine and hepatopancreas, of crayfish were investigated by high-throughput sequencing technology combined with histological analysis and flow cytometry. The findings suggested that <i>C. freundii</i> caused disruption of the intestinal microbiota, leading to intestinal inflammation and disrupting intestinal integrity. Meanwhile, <i>C. freundii</i> infection stimulates bile acid biosynthesis in the intestinal microbiota. Transcriptomic results showed significant upregulation of hepatopancreatic lipid degradation pathway and cytochrome P450-related pathways. Follow-up experiments confirmed a decrease in intracellular lipids and an increase in ROS and apoptosis. All the results indicated the disruption of intestinal-liver axis homeostasis due to disturbed intestinal microbiota may as a potential basis for <i>C. freundii</i> pathopoiesis in crayfish. These results provide new insights into the pathogenic molecular mechanisms of <i>C. freundii</i> in the infection of crayfish.