AMD Nitrososphaerota Archaeal Community

A novel archaeal community from acid mine drainage environments dominated by ammonia-oxidizing archaea (AOA) of the phylum Nitrososphaerota (formerly Thaumarchaeota). This community represents a unique nitrogen-cycling system operating at extremely low pH (2.5-4.5) where archaeal nitrifiers outcompete bacterial ammonia oxidizers. The dominant members include acidophilic AOA such as Candidatus Nitrosotalea devanaterra and Nitrososphaera-like archaea that possess extraordinary substrate affinity (Km 0.6-2.8 nM for NH3) and specialized adaptations for acidophily. These archaea oxidize ammonia to nitrite through the copper-containing ammonia monooxygenase (AMO) enzyme while maintaining cytoplasmic pH homeostasis in extremely acidic environments. The community also includes supporting acidophilic archaea from Thermoplasmata (Ferroplasma, Acidiplasma) that provide ecosystem services including organic matter processing and metal tolerance. Unique features include: (1) Amt-type ammonium transporters enabling NH4+ uptake rather than NH3 diffusion, (2) urea hydrolysis pathways providing localized ammonia generation, (3) extensive cell surface glycosylation reducing proton permeability, and (4) metabolic cooperation with nitrite-oxidizing bacteria (Nitrospira, Leptospirillum) completing the nitrification pathway. This system demonstrates how archaeal nitrifiers dominate nitrogen cycling in acidic environments where bacterial counterparts cannot function, with AOA abundance 3-10 fold higher than AOB in AMD sediments. The community thrives in acid sulfate soils, acid mine drainage sediments, and acidic tailings, representing a critical component of nitrogen cycling in the 30% of Earth's soils with pH <5.5. Based on genomic data from NCBI BioProject PRJNA1261802 and related AMD archaeal community studies.