High temperature stress induced oxidative stress, gut inflammation and disordered metabolome and microbiome in tsinling lenok trout.

Tsinling lenok trout (Brachymystax lenok tsinlingensis Li) is a species of cold-water salmon that faces serious challenges due to global warming. High temperature stress has been found to damage the gut integrity of cold-water fish, impacting their growth and immunity. However, limited research exists on the causal relationship between gut microbial disturbance and metabolic dysfunction in cold-water fish induced by high temperature stress. To address this gap, we conducted a study to investigate the effects of high temperature stress (24 °C) on the gut tissue structure, antioxidant capacity, gut microorganisms, and metabolome reactions of tsinling lenok trout. Our analysis using 16 S rDNA gene sequencing revealed significant changes in the gut microbial composition and metabolic profile. Specifically, the abundance of Firmicutes and Gemmatimonadetes decreased significantly with increasing temperature, while the abundance of Bacteroidetes increased significantly. Metabolic analysis revealed a significant decrease in the abundance of glutathione, which is synthesized from glutamate and glycine, under high temperature stress. Additionally, there was a notable reduction in the levels of adenosine, inosine, xanthine, guanosine, and deoxyguanosine, which are essential for DNA/RNA synthesis. Conversely, there was a significant increase in the abundance of D-glucose 6 P. Furthermore, high temperature stress adversely affects intestinal structure and barrier function. Our findings provide valuable insights into the mechanism of high temperature stress in cold-water fish and serve as a foundation for future research aimed at mitigating the decline in production performance caused by such stress.