# Characteristics of the Gut Microbiota in Different Segments of the Gastrointestinal Tract of Big-Eyed Bamboo Snake (Pseudoxenodon macrops)

## TL;DR

This study explores the gut microbiota of the Big-eyed Bamboo Snake in different parts of its gastrointestinal tract, revealing unique microbial communities and functions.

## Contribution

The study provides the first comparative analysis of gut microbiota across different intestinal segments in the Big-eyed Bamboo Snake.

## Key findings

- The small intestine has a unique microbial community structure and distinct metabolic functions compared to other intestinal segments.
- Bacteroides, Citrobacter, and Clostridium are significantly more abundant in the large intestine than in the small intestine.
- Functional annotations show significant differences in KEGG and CAZy level 2 functions between the stomach, small intestine, and large intestine.

## Abstract

The gut microbiota of animals is a complex micro-ecosystem that plays a crucial role in the physiological processes of the host, including metabolism, immunity, growth and development, behavioral regulation, and disease progression. Meanwhile, its activities and composition are influenced by genetic background, diet, sample sources, and the health status of the host. However, the studies, either inside or outside of China, on the gut microbiota of vertebrates mainly focus on mammals, and less than 10% of the studies are conducted on non-mammalian animals. In this study, we analyzed the microbial composition and functional prediction across different intestinal segments of the Big-eyed Bamboo Snake (Pseudoxenodon macrops). We found that the small intestine contains a unique community structure, and different intestinal segments exhibit distinct metabolic functions. Our findings provide insights into the comprehensive understanding of evolution and ecology of snakes, as well as on the development of the conservative strategies for these animals.

Snakes are model animals to study energy balance, but studies on the gut microbiota of the animals are rather scarce. To fill the gap, we used metagenome sequencing to investigate the microbial community composition and adaptability in the stomach, small intestine, and large intestine of Big-eyed Bamboo Snake. The results showed that there was no significant differences in α-diversity among different gastrointestinal segments. Pseudomonadota, Bacteroidota, and Bacillota were the most abundant phyla. The dominant genera in the stomach and small intestine were similar, while those in the large intestine were distinct. The abundance of Bacteroides, Citrobacter and Clostridium was significantly higher in the large intestine than in the small intestine. The LEfSe analysis revealed that the small intestine had the most characteristic bacteria, with a total of 20 species, while the stomach and large intestine each had two species. Additionally, in the current study, we also focused on the impact of the microbial community structure on functions through functional annotations in the KEGG and CAZy. There were significant differences in the KEGG level 2 between the stomach and the small intestine. The LEfSe analysis revealed the differences in the CAZy level 2 between the large intestine and the small intestine. Overall, our study provided a comparative and contrastive analysis of the gut microbiota in different gastrointestinal segments of Big-eyed Bamboo Snake, offering valuable insights for the co-evolution mechanism of the host and the gut microbiota.