Temperature Elevation Alters the Gut Antibiotic Resistome and Carbohydrate-Active Enzymes in the Desert Lizard Eremias roborowskii

In the context of global warming, the resulting persistent thermal stress has become a critical environmental factor influencing the structural and functional homeostasis of gut microbiota in reptiles. In this study, Eremias roborowskii, a desert lizard endemic to the extreme heat conditions of the Turpan Basin, was selected as an ideal model for evaluating the ecological impacts of global warming. Meanwhile, a 60-day controlled laboratory experiment was conducted, exposing the lizards to normal (30 °C ± 1 °C), elevated (37 °C ± 1 °C), and high (42 °C ± 1 °C) temperatures to reflect future climate scenarios. Using shotgun metagenomic sequencing, the gut microbiota was characterized to investigate the dynamics of the antibiotic resistance genes (ARGs) and carbohydrate-active enzymes (CAZymes) under heat stress. The results reveal that elevated temperature selectively promotes heat-tolerant gut microbiota, such as Tetragenococcus and Faecalicatena, by altering host energy metabolism and modulating heat stress adaptation to maintain intestinal homeostasis. Moreover, the observed increase in resistome diversity and richness under elevated temperature may be attributed to temperature-induced shifts in gut microbial composition, particularly the enrichment of heat-tolerant ARG-carrying bacterial taxa. Metabolic changes in CAZymes were caused by gut microbiota remodeling, which optimized carbon utilization and preferentially allocated cell wall synthesis and repair. Furthermore, the pentose phosphate pathway and amino acid biosynthesis pathways were upregulated, providing NADPH for antioxidant defense and precursors for protein synthesis, respectively, thereby contributing to the maintenance of microbial cellular homeostasis. Our study provides a theoretical basis for understanding functional gene adaptation strategies in wildlife microbiomes due to climate change.