Related Experiment Video
Updated: Jun 20, 2026
09:45
Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Published on: July 24, 2016
Iron respiration by Acidiphilium cryptum at pH 5
Azize Azra Bilgin1, JoAnn Silverstein, Joy D Jenkins
1Department of Civil, Environmental and Architectural Engineering, University of Colorado, Engineering Center ECOT 441, 1111 Engineering Drive, CB 428, Boulder, CO 80309, USA. abilgin@arcadis-us.com
FEMS Microbiology Ecology
|August 29, 2009
Summary
Acid-loving iron-respiring bacteria like Acidiphilium cryptum can grow at higher pH levels, aiding in the restoration of acid mine drainage sites by creating conditions favorable for other bacteria.
Area of Science:
- Microbiology
- Environmental Science
- Biogeochemistry
Background:
- Acid mine drainage (AMD) poses significant environmental challenges, characterized by low pH and high metal concentrations.
- Restoration of AMD sites often involves transitioning from acidic to circumneutral conditions.
- Acidophilic microorganisms play a crucial role in the biogeochemical cycling of metals in acidic environments.
Purpose of the Study:
- To investigate the growth and iron respiration of Acidiphilium cryptum at pH levels above 4.5.
- To determine the potential of A. cryptum in facilitating the pH transition during AMD site remediation.
- To understand the mechanisms of iron respiration and precipitation under varying pH conditions.
Main Methods:
- Incubation of Acidiphilium cryptum ATCC 33463 in liquid medium with Fe(III) sulfate and glucose.
- Initial aerobic conditions followed by sealed incubation to induce microaerophilic/anaerobic respiration.
- Monitoring of pH, soluble Fe(II), and Fe(III) species throughout the experiment.
Main Results:
- Significant iron respiration by A. cryptum was observed under microaerophilic conditions.
- The medium pH increased from 4.5 to 6, indicating a transition towards circumneutral conditions.
- Precipitated ferric iron species were utilized for respiration, and Fe(II) precipitation as magnetite was suggested.
Conclusions:
- Acidiphilium cryptum exhibits a broad pH tolerance, enabling growth in conditions transitioning from acidic to neutral.
- This bacterium can contribute to AMD remediation by consuming ferrous iron and increasing pH.
- A. cryptum may establish conditions conducive to neutrophilic bacteria, such as sulfate reducers, promoting overall site recovery.
Related Concept Videos
01:24Microbes and Other Elemental Cycles
Microbial activity plays a pivotal role in the biogeochemical cycling of iron and manganese, especially at the redox gradients characteristic of stratified aquatic environments. These cycles are driven by microbial transformations between oxidized and reduced forms of the metals, allowing organisms to exploit them for metabolic energy and structural purposes.Iron Cycling Across Redox GradientsIn neutral, oxygen-rich surface waters, iron is predominantly found in its oxidized, insoluble ferric...
01:28Anoxygenic Phototrophic Bacteria
Anoxygenic phototrophic bacteria are a diverse group of microorganisms that perform photosynthesis without producing oxygen. They primarily include purple sulfur bacteria, purple nonsulfur bacteria, green sulfur bacteria, and green nonsulfur bacteria. These bacteria are classified into the Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Chlorobi, and Chloroflexi lineages, each with distinct physiological and ecological adaptations.Purple sulfur bacteria belong to the...
01:28Microbial Nutrition
Organisms exhibit remarkable metabolic diversity, categorized based on how they acquire energy and carbon. These strategies enable survival in various ecological niches and are essential for maintaining energy flow and nutrient cycling within ecosystems.Energy and Carbon SourcesOrganisms are classified as phototrophs or chemotrophs based on energy acquisition. Phototrophs use light as their energy source, while chemotrophs rely on oxidizing chemical compounds. Further differentiation arises...
01:19Acid Mine Drainage
Mining activities that disturb sulfide-rich rocks, particularly those containing pyrite (FeS₂), initiate a cascade of geochemical and microbiological processes with serious environmental implications. When exposed to air and water, pyrite undergoes oxidation, releasing sulfate, ultimately forming sulfuric acid and mobilizing heavy metals into surrounding water systems. This phenomenon, known as acid mine drainage (AMD), results in low pH waters laden with toxic elements that threaten aquatic...
01:27Diversity of Archaea III
Crenarchaeota, a prominent phylum of Archaea, is remarkable for its ability to thrive in extreme environments characterized by high temperatures and acidity. These microorganisms inhabit sulfuric hot springs, volcanic systems, and submarine hydrothermal vents, where temperatures often exceed 100°C. The unique adaptations of Crenarchaeota not only allow survival under such extreme conditions but also provide insights into the mechanisms of life in primordial Earth-like environments.Morphological...
01:30Anoxygenic Photosynthesis
Anoxygenic photosynthesis is a phototrophic process that captures light energy to drive carbon fixation without producing molecular oxygen. Unlike oxygenic photosynthesis, which utilizes water as an electron donor and releases oxygen, anoxygenic phototrophs use alternative electron donors such as hydrogen sulfide (H₂S), elemental sulfur (S⁰), or thiosulfate (S₂O₃²⁻). This process is carried out by diverse groups of bacteria, including purple bacteria, green sulfur bacteria, heliobacteria, and...