Seasonal shift in gut microbiome diversity in wild Sichuan takin () and environmental adaptation.

In this study, we investigated the change in microbiome composition of wild Sichuan takin () during winter and spring and analyzed the physiological implications for such changes. Diversity analyses of the microbiome (average 15,091 high-quality reads per sample) in 24 fecal samples (15 from winter, 9 from spring) revealed that spring samples had higher species diversity and were compositionally different from winter samples (P < 0.05). Taxonomic composition analysis showed that the relative abundance increased in spring for (2.7% vs. 0.9% in winter, P < 0.001) and (1.9% vs. 1% in winter, P < 0.05). Substantial increases in relative abundance of and were identified in spring and winter, respectively. Mann-Whitney U and ANCOM identified seven differentially abundant genera: , , 1, UCG 008, 2 and . All seven genera were significantly more abundant in spring (average 0.016-1.2%) than winter (average 0-0.16%), with the largest difference found in (1.21% in spring vs. 0.16% in winter). The other six genera were undetectable in winter. Functional prediction and pathway analysis revealed that biosynthesis of cofactors (ko01240) had the highest gene count ratios in the winter, followed by the two-component system (ko02020). Seasonal variation affects the gut microbiomes in wild Sichuan takins, with winter associated with lower species diversity and spring with enrichment of cellulose-degrading genera and phytopathogens. Such changes were crucial in their adaptation to the environment, particularly the difference in food abundance.