Characteristics of Microbiota in Different Segments of the Digestive Tract of Lycodon rufozonatus

SIMPLE SUMMARY: Microorganisms are widely distributed in the skin, respiratory tract, digestive tract, external auditory tract, and urogenital tract of animals, with the highest microbiota abundance in the digestive tract. Considering the vital role of intestinal microbiota in nutrient metabolism, immunity, neuroregulation, and curing of disease, animal intestinal microbiota have become a research hotspot in conservation biology. The intestinal microbiota of mammals are dominated by Firmicutes and Bacteroidetes. The avian gut microbiota are similar to those of mammals at the phylum level and primarily consist of Bacteroidetes, Firmicutes, and Proteobacteria. Proteobacteria and Firmicutes dominated the bacterial communities of the insect gut. However, relatively little research has been conducted on reptiles, particularly snakes. In this study, the composition of the intestinal microbial community and its ecological adaptation were investigated in the different segments of the gastrointestinal tract of Lycodon rufozonatus specimens. We found that microbial diversity was higher in the stomach than that in the small and large intestines, and the microbes were involved in metabolic processes. Our results provide insights into the comprehensive understanding of the evolution and ecology of snakes and the formulation of conservation measures for these animals. ABSTRACT: The gastrointestinal tract of animals contains microbiota, forming a complex microecosystem. Gut microbes and their metabolites can regulate the development of host innate and adaptive immune systems. Animal immune systems maintain intestinal symbiotic microbiota homeostasis. However, relatively few studies have been published on reptiles, particularly snakes, and even fewer studies on different parts of the digestive tracts of these animals. Herein, we used 16S rRNA gene sequencing to investigate the microbial community composition and adaptability in the stomach and small and large intestines of Lycodon rufozonatus. Proteobacteria, Bacteroidetes, and Firmicutes were most abundant in the stomach; Fusobacteria in the small intestine; and Proteobacteria, Bacteroidetes, Fusobacteria, and Firmicutes in the large intestine. No dominant genus could be identified in the stomach; however, dominant genera were evident in the small and large intestines. The microbial diversity index was significantly higher in the stomach than in the small and large intestines. Moreover, the influence of the microbial community structure on function was clarified through function prediction. Collectively, the gut microbes in the different segments of the digestive tract revealed the unique features of the L. rufozonatus gut microbiome. Our results provide insights into the co-evolutionary relationship between reptile gut microbiota and their hosts.