Australian Lead Zinc Polymetallic Tailings Consortium

A stratified microbial community from abandoned polymetallic mine tailings in Western Australia, characterized by vertical zonation of acidophilic and anaerobic organisms across steep pH and redox gradients. This system represents a naturally acidifying sulfidic tailings dump where oxidative weathering of Pb-Zn sulfide minerals drives extreme environmental heterogeneity and microhabitat specialization. The upper oxidized layer (pH 1.5-3.0) is dominated by iron- and sulfur-oxidizing acidophiles including Acidithiobacillus ferrooxidans (dual Fe/S oxidation) and Leptospirillum ferriphilum (specialized Fe oxidation), which generate ferric iron and sulfuric acid that mobilize lead, zinc, copper, and iron from sulfide minerals including galena (PbS), sphalerite (ZnS), and chalcopyrite (CuFeS₂). The intermediate chemocline exhibits dramatic pH transitions (pH 3-5) where Ferroplasma acidarmanus thrives in highly acidic microniches while facultative acidophiles transition to neutral conditions. The deeper sediment layer (pH 5-7) harbors anaerobic metal-reducing bacteria including Geobacter metallireducens that reduce ferric iron to ferrous iron using organic carbon, creating redox cycling between oxic and anoxic zones. Metagenome-assembled genomes (MAGs) reveal extensive microhabitat partitioning, with distinct populations specializing in surface oxidation, chemocline transitions, or deep anaerobic processes. Metal concentrations reach toxic levels (Pb: hundreds mg/kg, Zn: thousands mg/kg, Cu: hundreds mg/kg, Fe: up to 30% w/w), selecting for metal-resistant populations. This abandoned tailings system demonstrates natural biogeochemical cycling without active mining, with microbial communities driving ongoing metal mobilization (upper layers) and potential natural attenuation (deeper layers). The MAG-resolved metagenomics approach reveals cryptic microbial diversity including novel acidophilic lineages adapted to polymetallic stress, providing insights into bioremediation strategies and microbial evolution in extreme anthropogenic environments.