Comprehensive catalog of gut microbial genomes in Asian elephants: insights from shotgun metagenomics

The gut microbiota plays a crucial role in metabolism, immune regulation, and ecological adaptation of mammals. Although significant advancements have been made in shotgun metagenomic sequencing and the emergence of algorithms for generation of metagenome-assembled genomes (MAGs), a comprehensive investigation of the gut microbiota at the species level of wild mammals, among these the Asian elephant (Elephas maximus), is still lacking. Here, based on a total of 82 fresh fecal samples collected from Asian elephants residing in distinct regions of the Yunnan Province, we established a comprehensive genome catalog containing 1421 species-level genome bins (SGBs) and a gene catalog comprising 44,596,628 non-redundant genes covering the gut microbiota composition of representative Asian elephant populations. At the species level, 1368 bacteria and 53 archaea were identified, and more than 93% of the SGBs remained unclassified, indicating that there are a large number of potential new species in the Asian elephant gut microbiota. At the functional level, carbohydrate hydrolases, biosynthetic gene clusters, and metabolic pathways dominated the gut microbiome of Asian elephants. Lifestyle and migration affected the composition and functional potential of the gut microbiota of Asian elephants. A northward migration was accompanied by an increase in gut microbiota diversity, an increase in the abundance of the phylum Bacteroidota, and a decrease in the presence of potentially pathogenic genera. In contrast, a southward migration of elephant herds was accompanied by exposure to unfavorable environments, with changes in gut microbiota including increased xenobiotic degradation and metabolic capacity. We constructed comprehensive catalogs of gut microbial genes and genomes representative for Asian elephant populations, providing a valuable data resource for future research. Our study elucidates migration and lifestyle may modulate the composition and functionality of the gut microbiota in Asian elephants, offering critical insights for monitoring their health and enhancing conservation strategies for wild populations.