Module 9: Acid Mines

• microbes in acid mines accelerate iron oxidation rates at low pH
• 2 iron pyrite steps: biotic iron oxidation and pyrite dissolution
• biotic iron oxidation releases sulfuric acid and Fe3+
• in pyrite dissolution Fe3+ reacts with water to make acid and rust colored precipitate
• acid mine microbes are mainly nitrospira: biofilm formation and nitrogen fixation
• what is the grow method of primary producers in acid mines?

  mainly chemolithoautotrophs
• chemolithoautotrophs get energy from sulfur oxidation and compounds, carbon from CO2, and nitrogen from nitrogen fixation
• leptospirillum ferrooxidans: gram negative, dominant primary producer
• leptospirillum ferroxidans are chemolithoautotrophs: oxidize Fe2+ with oxygen and CO2 fixation by reductive TCA cycle
• what are the unique features of Fe oxidation?

  • reverse electron flow
  • Rus in periplasm
  • cyc2 in outer membrane
• ferroplasma acidarmanus: FeS2 oxidation by reductive acetyl-coA pathway
• eukaryotes in acid mines grow chemoheterotrophically on dead primary producers and excretions
• eukaryotes in acid mines are fungi and protists (graze on bacteria)