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Gut microbiotas have important impacts on host health, reproductive success, and survival. While extensive research in mammals has identified the exogenous (e.g. environment) and endogenous (e.g. phylogeny, sex, and age) factors that shape the gut microbiota composition and functionality, yet avian systems remain comparatively less understood. Shorebirds, characterized by a well-resolved phylogeny and diverse life-history traits, present an ideal model for dissecting the factors modulating gut microbiota dynamics. Here, we provide an insight into the composition of gut microbiota in two high-altitude (ca. 3200 m above sea level) breeding populations of Kentish plover ( Charadrius alexandrinus ) and Tibetan sand plover ( Charadrius altrifrons ) in the Qinghai-Tibetan Plateau, China. By analysing faecal bacterial communities using 16S rRNA sequencing technology, we find a convergence in gut microbial communities between the two species, dominated by Firmicutes, Proteobacteria , and Bacteroidetes . This suggests that the shared breeding environment potentially acts as a significant determinant shaping their gut microbiota. We also show sex- and age-specific patterns of gut microbiota: female adults maintain a higher diversity than males, and juveniles are enriched in Rhizobiaceae and Exiguobacterium due to their vegetative food resource. Our study not only provides a comprehensive descriptive information for future investigations on the diversity, functionality, and determinants of avian microbiomes, but also underscores the importance of microbial communities in broader ecological contexts., Competing Interests: The authors declare that they have no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Objective: Paracin 1.7 was a bacteriocin extracted from Lactobacillus paracasei HD1.7. In this study, we investigated quorum-sensing mechanism that regulates the metabolism of Paracin 1.7 in strain HD1.7., Methods: The antibacterial activity of strain HD1.7 under different growth conditions was analyzed using an agar-well diffusion method, and the cell density was controlled by adjusting nutrient levels in the culture medium., Results: The antibacterial activity of strain HD1.7 depended on cell density. Strain HD1.7 exhibited the antibacterial activity when the cell density reached a threshold (OD600 of 0.8 and cell dried weight of 0.3311 g/L). Addition of different concentrations of a signaling molecule in the supernatant of the fermentation broth affected the antibacterial activity. After removing the signal molecule, the antibacterial activity was significantly decreased., Conclusion: Paracin1.7 was the quorum-sensing signaling molecule in the HD1.7 fermentation broth and it could be auto-induced. The antibacterial activity of Paracin1.7 was regulated by the quorum-sensing system in HD1.7.