Prokaryotic assemblages in bromeliad phytotelmata reflect shared and host-specific patterns in campos rupestres

Bromeliads play a key ecological role in many Brazilian ecosystems, particularly in campos rupestres (Brazilian rupestrian grasslands) , but face increasing threats from mining and extractive activities in the Iron Quadrangle region of Minas Gerais, Brazil. Their water-filled leaf axils, or phytotelmata, host diverse microbial communities that may influence host fitness, although the ecological drivers shaping these communities remain poorly understood, especially in endangered campo rupestre ferruginoso (ferruginous rupestrian grasslands). In this study, we used 16S rRNA gene sequencing and functional prediction (PICRUSt) to compare the prokaryotic communities in the phytotelmata of two co-occurring and morphologically distinct species, Aechmea nudicaulis and Vriesea minarum , from a conserved campo rupestre ferruginoso ( ferruginous rupestrian grasslands ) site in Serra da Piedade (Minas Gerais, Brazil). We hypothesized that differences in plant morphology and microenvironmental conditions between host species would result in distinct microbial community structure and functional potential. Although both species shared a microbial core, significant differences in alpha diversity, community composition and predicted functional profiles, were observed. The most abundant bacterial phyla were Proteobacteria, Verrucomicrobia, and Planctomycetes, while Euryarchaeota dominated among Archaea. Environmental variables such as pH, conductivity and inorganic carbon were correlated with community composition. Notably, predicted KOs associated with nitrogen and carbon cycling pathways showed differential abundance between the two host species. These findings indicate that bromeliad phytotelmata function as host- and environment-filtered microhabitats, supporting distinct and diverse microbial communities. Given their roles in nutrient cycling, such interactions may influence plant fitness and ecosystem functioning. Understanding these relationships is important for guiding conservation efforts in fragile montane systems.