Metagenomic Study Of Gut Microbiomes In Myrmecophagous Mammals

The adaptation of animals to food is a key step during their adapttive evolution.Other studies have shown that the co-evolution relationship between animal intestinal microbiome and host genome promoted animals to adapt to different dietary.Pangolins and anteaters are two most specified myrmecophagous mammals,belonging to different order.So far,studies has been conducted to investigate the intestinal microbial composition and community structure of myrmecophagous mammals based on 16S rRNA,functional genes in the whole genome and transcriptome of Malayan pangolin.However,the recognition of myrmecophagous mammalian intestinal microbial functional gene is not sufficient.Therefore,it is necessary to study intestinal microbial metagenome of myrmecophagous mammalian and comprehensively understand the molecular mechanism about dietary adaptability from"second genome" of host.In this study,we used Illumina MiSeq 2000 to sequence genome and obtained- 64.9Gb intestinal microbial metagenomic datas from six giant anteaters,two tamanduas and three pangolin.Assembled metagenomic datas individually and found that the mean length of the scaffolds' N50 is 2,946bp,1043896 open reading frames(ORF)were predicted.Then we identified the intestinal microbial species and functional genes.The analysis of intestinal micropopulations and functional genes with Principal Components Analysis(PCA)indicates that eleven samples are clustered with species.We also found that the giant anteater is closer with tamandua than pangolin which indicates that intestinals microbial community structure of giant anteaters and tamandua is more similar.Based on the published intestinal microbial metagenomic datas of 39 mammals which has different diet.we analyzed intestinal micropopulations and functional genes with Principal Components Analysis(PCA)and found that they are clustered by diet which confirmed that diet is main factor affecting the intestinal microbial community structure.Combined with metagenomic datas published and metagenomic datas of intestinal microorgnism which is sequenced by ourselves,we found that the bacterial genus of intestinal microbial flora in myrmecophagous mammals(pangolin,armadillo and echidna)mainly include Lactobacillus and Bacteroides,and the bacterial genus of giant anteater and tamandua are Prevotella and Bacteroides.It is noteworthy that compared to other mammals,ko00561/ko00564(lipid metabolism pathway),COG0406(phosphoglycerate mutase),GH23/GH73(Chitin metabolism),EC 2.6.1.16(hexosephosphate aminotransferase),EC 6.3.5.6/EC 6.3.5.7(amide aminotransferase)are richer in intestinal of myrmecophagous mammals which help a host to digest shellfish,protein and lipid.So intestinal microorgnism promote metabolism process of the host nutrients.This study is the first time to study the intestinal metagenome of giant anteater,tamandua and pangolin.It study their intestinal microbial community structure but also found the functional genes which may be related to the degradation of chitin and reveal intestinal microbial mechanism of diet adaptation in the myrmecophagous mammals.It provides a new idea and methodology for the future study about the evolution of animal adaptability.