Contemporary environmental variation determines microbial diversity patterns in acid mine drainage

Area of Science:

• Microbial Ecology
• Environmental Microbiology
• Extreme Environments

Background:

• Microorganisms inhabit diverse extreme environments, but their large-scale ecological distribution patterns and controlling factors remain poorly understood.
• Acid mine drainage (AMD) systems represent unique extreme environments characterized by low pH and high metal concentrations.

Purpose of the Study:

• To investigate the phylogenetic differentiation and distribution patterns of microbial communities in Southeast China's acid mine drainage (AMD) sites.
• To identify the key environmental factors driving microbial community structure in these harsh ecosystems.
• To determine the relative importance of environmental variation versus geographical distance in shaping microbial diversity in AMD systems.

Main Methods:

• Utilized bar-coded 16S rRNA pyrosequencing to analyze 59 microbial communities from diverse AMD sites.
• Employed phylogenetic diversity, phylotype richness, and pairwise UniFrac distance to estimate microbial diversity.
• Applied multivariate regression tree analysis to identify environmental predictors of microbial lineage abundance.

Main Results:

• Environmental variation, particularly solution pH, was the major factor explaining microbial community differences in AMD sites.
• Microbial diversity estimates (phylogenetic diversity, richness, UniFrac distance) strongly correlated with pH.
• Specific bacterial groups (Betaproteobacteria, Alphaproteobacteria, Euryarchaeota, Gammaproteobacteria, Nitrospira) showed distinct pH-dependent distribution patterns, with some adapted to moderate pH and others to acidic conditions.

Conclusions:

• Microbial diversity patterns in extreme AMD environments are predominantly predicted by contemporary environmental variation, especially pH, over geographical distance.
• pH acts as a significant selective pressure, driving the adaptation and distribution of acidophilic microorganisms globally.
• The findings provide crucial insights into the ecological principles governing microbial life in extreme environments.