The gut microbiome and metabolome of Himalayan Griffons(Gyps himalayensis):insights into the adaptation to carrion-feeding habits in avian scavengers

Background:Himalayan Griffons(Gyps himalayensis),large scavenging raptors widely distributed in Qinghai-Tibetan Plateau,have evolved a remarkable ability to feed on carcasses without suffering any adverse effects.The gut microbiome plays an important role in animal physiological and pathological processes,and has also been found to play a health protective role in the vulture adaptation to scavenging.However,the microbial taxonomic diversity(including nonculturable and culturable microbes),functions,and metabolites related to Himalayan Griffons have not been fully explored.Methods:In the present study,the 28 fecal samples of the Himalayan Griffons and 8 carrion samples were collected and sequenced using high-throughput 16 S rRNA gene sequencing methods to analyze the composition and functional structures of the microbiomes.Twelve fecal samples of the Himalayan Griffons were analyzed using untargeted Liquid Chromatography Mass Spectroscopy(LC-MS)to identify metabolites.We used different culture conditions to grow Himalayan Griffons gut microbes.Inhibitory effects of gut beneficial bacteria on 5 common pathogenic bacteria were also tested using the Oxford cup method.Results:According to the results of the culture-independent method,a high abundance of four major phyla in Himalayan Griffons were identified,including Fusobacteria,Firmicutes,Bacteroidetes,and Proteobacteria.The most abundant genera were Fusobacterium,followed by Clostridium_sensu_stricto_1,Cetobacterium,Epulopiscium,and Bacteroides.The predicted primary functional categories of the Himalayan Griffons'gut microbiome were associated with carbohydrate and amino acid metabolism,replication and repair,and membrane transport.LC-MS metabolomic analysis showed a total of 154 metabolites in all the fecal samples.Cultivation yielded 184 bacterial isolates with Escherichia coli,Enterococcus faecium,Enterococcus hirae,and Paeniclostridium sordellii as most common isolates.Moreover,7 potential beneficial gut bacteria isolated showed certain inhibition to 5 common pathogenic bacteria.Conclusions:Our findings broaden and deepen the understanding of Himalayan Griffons'gut microbiome,and highlighted the importance of gut microbiome-mediated adaptation to scavenging habits.In particular,our results highlighted the protective role of gut beneficial bacteria in the Himalayan Griffons against pathogenic bacteria that appear in rotten food resources.