Integrating free-living amoebae into climate-microbiome and One Health frameworks

Climate change is altering microbial ecosystems at a global scale, yet the role of free-living amoebae within these shifting microbiomes remains incompletely understood. Free-living amoebae occupy soil, water, air, and built environments, where they contribute to microbial diversity, regulate nutrient cycling, and host diverse bacterial, fungal, and viral microorganisms. As temperature, moisture, and land-use patterns change, amoebal behaviour and their associated microbiomes may shift in ways that may affect soil fertility, water quality, microbial network stability, and the persistence of opportunistic pathogens. Through grazing, amoebae regulate bacterial turnover and mineral nutrient release from microbial biomass, providing a mechanistic link between nutrient cycling and plant accessible nutrient pools that underpin soil fertility. Understanding these dynamics is essential for planetary microbiome research and for strengthening One Health approaches that link environmental, animal, and human health. Herein, we discuss free-living amoebae in the context of climate change, the planetary microbiome, and One Health, and consider how their ecological roles may relate to broader shifts in microbial systems. We synthesise current evidence linking free-living amoebae to climate-responsive microbiome dynamics and propose their inclusion within planetary microbiome and One Health frameworks as responsive ecological indicators. Integrating amoebae into surveillance, ecological modelling, and climate-adaptation strategies may improve predictive capacity for tracking climate-driven microbial change.