The role of microbiota in bovine tuberculosis: Characterizing bacterial communities across lungs, gut, and lymph nodes.

Animals with bovine tuberculosis (bTB) develop granulomatous lesions as part of a complex immune response to chronic antigenic stimulus involving innate and adaptive mechanisms; however, the association of the microbiota with the development of and susceptibility to bTB remains poorly understood. This study characterizes the bacterial communities at different body sites involved in the pathophysiology of bTB, highlighting the gut-lung axis and their association with disease. Lungs, gut, thoracic, and mesenteric lymph nodes samples were collected from 31 bovines from a single herd (n = 19 bTB; n = 12 controls). The samples were analyzed using high-throughput sequencing of the 16S rRNA gene. A significant difference in beta diversity was observed between the bTB and control groups only in the thoracic lymph nodes (p < 0.05), whereas no significant differences were detected in the other sites. LEfSe and GLM analyses showed different taxa significantly enriched in the control group: Eubacterium ventriosum, Lacticaseibacillus, Paucibacter, Clostridioides, Bdellovibrio/Bdellovibrionaceae and Rhodobacteraceae, some of them suggested by previous findings as taxa of interest in their potential as preventive or diagnostic candidates. Additionally, analysis of microbial correlations along the gut-lung axis identified distinct phylum-level associations between bTB and healthy groups, suggesting altered microbial patterns in bTB. These findings contribute to the understanding of bovine microbiota composition across organs, their association with bTB and the pathogenesis of bTB, highlighting microbial candidates for future validation for microbiota-based interventions and laying the groundwork for future studies exploring host-microbiota-pathogen interactions in the context of bTB.