Integrated Gut Microbiota and Metabolome Analysis Reveals Dysbiosis and Metabolic Disturbances in Diarrhea of the Complex-Toothed Flying Squirrel (Trogopterus xanthipes): Possible Mycotoxin-Induction?

The gut microbiota and its metabolic functions are critical for intestinal homeostasis, but their integrated responses to diarrhea remain poorly understood in non-model mammals, such as the complex-toothed flying squirrel (Trogopterus xanthipes). Here, we collected fecal samples from six captive animals with diarrhea and six healthy controls; the diarrheal animals had been provided with moldy corn, but mycotoxin levels were not measured. Fecal microbiota was profiled by full-length 16S rRNA sequencing and untargeted metabolomics with integrative analyses. Diarrheal animals showed significantly decreased fecal microbial alpha-diversity and distinct community separation. LEfSe analysis identified Lawsonia intracellularis and Streptococcus macedonicus as the most enriched taxa in the diarrhea group. Untargeted metabolomics revealed 2216 differential metabolites (1931 downregulated), primarily enriched in steroid hormone biosynthesis, arachidonic acid metabolism, and bile secretion pathways. Procrustes and Mantel tests confirmed significant microbiome–metabolome concordance (M2 = 0.422, p < 0.001). Spearman correlation networks showed that L. intracellularis was positively correlated with multiple differential metabolites, while S. macedonicus exhibited predominantly negative correlations. These findings suggest that diarrhea in T. xanthipes may be associated with moldy corn exposure and is accompanied by gut dysbiosis and metabolic disturbances. L. intracellularis and S. macedonicus may be associated with disease progression through pathways linked to lipid and bile acid metabolism and inflammation. This study provides novel microbial–metabolic insights into diarrhea in a medicinal mammal, supporting disease prevention and healthy breeding.