Studies On The Adaptive Changes In Gut Microbes And Its Metabolites Of Strauchbufo Raddei During Hibernation

Hibernation is an adaptive survival strategy that some vertebrates have evolved over time in response to unfavourable environments.During hibernation,vertebrates undergo a prolonged fasting process and therefore their energy sources are transformed during hibernation.Gut microbiota are involved in a wide range of vertebrate metabolic activities and play an important role in vertebrate growth and development,nutrient absorption and immune regulation,but the role of gut microbiota during vertebrate hibernation remains unclear.Most current research on gut microbiota in hibernating animals has focused on mammals,but amphibians have been largely neglected.In addition,there is a great research gap on the effects of hibernation on the amphibian gut metabolome.In this study,Strauchbufo raddei(S.raddei)was used as the research object.And artificial hibernation environment was constructed to simulate the hibernation state of S.raddei.The effects of hibernation on the survival environment of gut microbiota were investigated by histology and digestive enzyme activity assays,the changes of gut microbiota and metabolites before and after hibernation were investigated by microbiomics and metabolomics,and the potential functions of gut microbiota in the regulation of metabolism during hibernation of S.raddei were revealed by correlation analysis.The results showed that:(1)Compared with the active period,the structure of the small intestine in hibernating S.raddei was significantly altered,as evidenced by by the atrophy of the intestinal villi in the duodenum and ileum,and the height of intestinal villi and intestinal epithelial cells in duodenum were decreased significantly.(2)Trypsin and lipase activities were significantly lower in hibernating S.raddei than in the active period.(3)The diversity of gut microbiota in hibernating S.raddei was significantly reduced and the structure of the gut microbiota changed,with the highest relative abundance of Firmicutes in the active phase and Proteobacteria in the hibernation phase.(4)Some bacteria could be used as biomarkers to distinguish between active and hibernating groups,including Pseudomonas,Vibrio,Ralstonia,and Rhodococcus.(5)The gut microbiota of hibernating S.raddei was more resistant to environmental stress.(6)The metabolic levels of hibernating S.raddei are suppressed,differential metabolites were highly concentrated in fatty acid biosynthesis,and differential metabolites that are significantly enriched during hibernation have potential functions in energy metabolism and immune regulation.(7)Gut microbiota might be involved in the metabolic regulation of S.raddei during hibernation.Taken together,this study reveals for the first time the positive responses and adaptive changes in the gut microbiota and their metabolites of S.raddei to the hibernating environment,providing greater insight into our understanding of the adaptive evolution and developmental history of amphibians,as well as deepening our understanding of the different survival strategies of vertebrates in extreme environments.