Comparison of bacterial communities associated with the skin of Ambystoma mexicanum under laboratory conditions and during its controlled presence in the chinampas of Xochimilco.

The central objective of this study is to compare the composition, structure, and functionality of bacterial communities associated with the skin of the axolotl Ambystoma mexicanum between controlled laboratory conditions and the natural environments of the chinampas of Xochimilco, in order to understand how environmental factors influence their diversity and the adaptive potential of the host. Given the critical conservation situation of the axolotl, an endangered endemic species whose habitat has been degraded by pollution, fragmentation, and anthropogenic pressure, this research acquires strategic relevance by demonstrating the role of its cutaneous bacterial communities as an essential symbiotic component for the health of the organism. The results show that while the homogeneous laboratory environment favors less diverse and functionally restricted microbial communities, chinampa systems promote more complex, resilient, and functionally specialized assemblages, enriched with taxa linked to the production of antimicrobial metabolites, the degradation of organic compounds, and resistance to contaminants. These differences reflect the ability of axolotl skin bacteria to maintain homeostasis and defend the host against threats such as Batrachochytrium dendrobatidis through competitive exclusion mechanisms, chitinase synthesis, siderophore production, and quorum sensing regulation. The research also highlights critical parameters such as dissolved oxygen, ammonium, and fecal coliform load as determining factors in the configuration of these symbiotic communities. Our findings provide scientific grounds to strengthen conservation strategies, both in situ and in "chinampa-refuge" models, as well as ex situ, by optimizing captive conditions that favor protective and robust microbial communities. In this sense, ensuring the viability of the Mexican axolotl requires integrating the conservation of its bacterial communities as an essential pillar to sustain its health and resilience in an increasingly adverse environmental context.