Microbial Ecology of Acid Mine Drainage Systems

Acid mine drainage systems arise when sulphide minerals are exposed to oxygen and water, generating acidic waters rich in dissolved metals. Despite extreme conditions of low pH, high metal concentrations and limited organic carbon, diverse microbial communities colonise these habitats. Chemolithotrophic bacteria and archaea drive the oxidation of iron and sulphur, coupling mineral dissolution to energy conservation and thereby sustaining ecosystem function. Interactions among acidophiles, including syntrophic partnerships between iron- and sulphur-oxidisers, underpin biogeochemical cycling. Rare taxa often contribute key functions, such as nitrogen fixation or organic matter degradation, while viruses can modulate community metabolism through auxiliary metabolic genes. Spatial gradients in pH, oxygen and metals create microhabitats—water column, sediments and biofilms—each hosting distinct assemblages of bacteria, archaea and eukaryotes. Understanding microbial adaptation mechanisms, from metal resistance systems to acid-tolerant membrane biochemistry, is essential for both fundamental ecology and the development of bioremediation strategies that harness native microbiota to attenuate acidity and sequester metals.

Research from Nature Portfolio

Recent studies of mine tailings undergoing ecological restoration have demonstrated that revegetation can alter microbial community structure along soil profiles. Surface soils under pioneer plants show increased pH and shifts in dominant bacterial phyla, with Alphaproteobacteria and Acidobacteria becoming more abundant at shallow depths, while deeper layers remain relatively unchanged. These changes correspond to increased nitrogen-fixing activity and improved soil function.

Investigations into phytostabilisation of sulphidic tailings reveal a directional shift from lithotroph-dominated to organotroph-dominant communities following amendment and plant growth. Extremophilic iron- and sulphur-oxidisers give way to heterotrophic genera more typical of natural soils, suggesting that initial plant establishment and substrate amendment can steer microbial succession toward communities better suited to long-term soil development and stability.

Microbial Ecology of Acid Mine Drainage Systems publication trend

The graph below shows the total number of articles in microbial ecology of acid mine drainage systems across all publications each year (not limited to Nature Index journals).

Technical terms

Acid mine drainage (AMD): Water with low pH and elevated metal concentrations produced by oxidative dissolution of sulphide minerals.

Chemolithotrophy: Metabolic strategy in which organisms derive energy by oxidising inorganic compounds such as ferrous iron or reduced sulphur species.

Metagenomics: Culture-independent analysis of the collective genomes of a microbial community to assess diversity and functional potential.

Biofilm: Structured microbial consortium attached to a surface and embedded in an extracellular matrix, often enhancing resistance to stress.

Extremophile: Organism adapted to thrive under environmental extremes, such as high acidity, temperature or metal toxicity.

References

1. Microbial diversity and metabolic networks in acid mine drainage habitats. Frontiers in Microbiology (2015).
2. Bacterial, Archaeal, and Eukaryotic Diversity across Distinct Microhabitats in an Acid Mine Drainage. Frontiers in Microbiology (2017).
3. Insights into ecological role of a new deltaproteobacterial order Candidatus Acidulodesulfobacterales by metagenomics and metatranscriptomics. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2019).
4. Ecological restoration alters microbial communities in mine tailings profiles. Scientific Reports (2016).
5. Archaea dominate the microbial community in an ecosystem with low-to-moderate temperature and extreme acidity. Microbiome (2019).
6. From lithotroph- to organotroph-dominant: directional shift of microbial community in sulphidic tailings during phytostabilization. Scientific Reports (2015).