Fecal Microbiota Structure and Pathogen Carriage Characteristics of Tadorna ferruginea on the Qinghai-Tibet Plateau

Objective To analyze the structure of fecal bacterial communities in the ruddy shelduck (Tadorna ferruginea) on the Qinghai-Tibet Plateau (QTP), characterize the distribution of pathogenic bacteria, evaluate their potential ecological and public health significance, and provide basicline data for biosafety surveillance and bacterial disease prevention in this plateau region.

Methods A total of 26 fecal samples was collected from ruddy shelducks. Bacterial isolation was performed using tryptic soy agar (TSA), brain heart infusion agar (BHIA), and R2A agar under different conditions: two temperatures (28 ℃ and 37 ℃, and two atmospheric conditions (aerobic and microaerobic with 5% CO₂). Isolated strains were identified by full-length 16S rRNA gene sequencing. Differences in bacterial community composition under various culture conditions were analyzed, and potential pathogens were screened.

Results A total of 1150 bacterial strains was isolated and identified, belonging to 23 families, 44 genera, and 117 species. The dominant genera were Pseudomonas (24.43%), Arthrobacter (21.65%), and Carnobacterium (13.65%). Among these isolates, 29 species were identified as pathogenic or potentially pathogenic, including 7 zoonotic species (17 strains), 16 human pathogenic species (134 strains), and 6 animal pathogenic species (120 strains). Among the three media, TSA yielded the highest number of genera (24 genera), while BHIA recovered the highest number of species (43 species) under microaerobic conditions. The combination of 28 ℃ and microaerobic conditions was superior to 37 ℃ and aerobic conditions in terms of the numbers of strains, species, and genera recovered.

Conclusion The feces of ruddy shelducks in the QTP harbor a diverse range of culturable bacteria, including several zoonotic and opportunistic pathogens of public health concern. TSA and BHAI are suitable for broad-spectrum isolation of intestinal bacteria from this species, and the combination of 28 ℃ with microaerobic conditions enhances bacterial diversity. This study provides an experimental basis for the exploration of gut microbial resources in wild birds and for the surveillance of pathogenic bacteria carriage.