1-5 Beichenxilu, Chaoyang District National Research Center for Wildlife-Born Diseases, Institute of Zoology, Chinese Academy of Sciences Beijing
Beijing Milu Ecological Research Center, Beijing, China
Beijing Capital International Airport Co., Ltd., Beijing, China.
This study was supported by Beijing Wildlife Rescue Center, China, the National Key Research and Development Program of China (No. 2022YFC2601602), the Major Program of National Natural Science Foundation of China (No. 32090023), and National Forestry and Grassland Administration, China.
The gut microbiota plays a crucial role in interacting with the host's physiological system and providing essential ecosystem services. It is known that diet can affect the composition of the gut microbiota, while the gut microbiota can also help the host adapt to specific dietary habits. As a facultative scavenger urban bird, the carrion crow (Corvus corone) is one of the hosts of high-abundance pathogen due to its facultative scavenging behavior. However, carrion crows rarely get sick, which is related to their unique physiological adaptation ability. The role of the gut microbiota in this process remains incompletely understood. In this study, we performed a comparative analysis using 16S rRNA amplicon sequencing technology, analyzing the colonic contents of carrion crows and 16 other bird species with different diets in Beijing, China. Our findings revealed that the predominant gut microbiota of the carrion crow primarily comprises Proteobacteria (75.51%) and Firmicutes (22.37%). We observed significant differences in the relative abundance of Enterococcus faecalis between groups, suggesting that Enterococcus faecalis may serve as a biomarker for carrion crows' facultative scavenging behavior. Subsequently, we isolated Enterococcus faecalis derived from carrion crows and conducted transplantation experiments in model mice to confirm the protective effects of this bacterial community against Salmonella infection. The results demonstrated that Enterococcus faecalis can downregulated the expression of pro-inflammatory cytokines TNF-α, IFN-γ, and IL-6, prevented the colonization of Salmonella, and regulated the composition of gut microbiota in mice, thereby modulating the host's immune regulatory capacity. Finally, we demonstrated that the Enterococcus faecalis plays an immunoregulatory and anti-pathogen role in carrion crows during scavenging behavior, providing a typical case of how the gut microbiota can protect diet-specialized hosts.