Related Experiment Video
Updated: Jun 26, 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 requirement for Mn(II) oxidation by Leptothrix discophora SS-1
Iman A El Gheriany1, Daniela Bocioaga, Anthony G Hay
1School of Civil and Environmental Engineering, Cornell University, Ithaca, New York 14853, USA.
Applied and Environmental Microbiology
|December 31, 2008
Summary
Iron limitation reduces the manganese(II) oxidation ability of Leptothrix discophora SS-1. This suggests iron is crucial for manganese oxidation, possibly as a component of the manganese-oxidizing factor (MOF).
Area of Science:
- Biogeochemistry
- Microbial Metabolism
- Environmental Science
Background:
- Biogenic manganese oxides are formed through microbial oxidation of Mn(II), a critical process in manganese geochemical cycling.
- Leptothrix discophora SS-1 is a model bacterium for studying extracellular Mn(II) oxidation, often attributed to a manganese-oxidizing factor (MOF).
Purpose of the Study:
- To investigate the influence of iron availability on the rate of extracellular Mn(II) oxidation by Leptothrix discophora SS-1.
- To explore the mechanistic role of iron in Mn(II) oxidation and its potential interaction with the MOF.
Main Methods:
- Culturing Leptothrix discophora SS-1 in media with varying iron concentrations (limited vs. sufficient).
- Evaluating extracellular Mn(II) oxidation rates under different iron conditions.
- Assessing the impact of copper supplementation and analyzing mofA gene transcript levels via quantitative PCR.
Main Results:
- Iron-limited cultures exhibited significantly reduced Mn(II) oxidation rates compared to iron-sufficient cultures.
- The addition of copper did not restore Mn(II) oxidation in iron-limited conditions.
- Iron limitation did not affect mofA gene transcription levels, suggesting post-transcriptional regulation.
Conclusions:
- Iron availability is critical for efficient Mn(II) oxidation by Leptothrix discophora SS-1.
- The data suggest iron may be a direct component of the MOF or indirectly influence Mn(II) oxidation through other cellular functions.
- Further research is needed to elucidate the precise mechanistic role of iron in this biogeochemical process.
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...
01:21Radical Oxidation of Allylic and Benzylic Alcohols
Activated manganese(IV) oxide can selectively oxidize allylic and benzylic alcohols via a radical intermediate mechanism. Primary allylic alcohols are oxidized to aldehydes, while secondary allylic alcohols yield ketones. The redox reaction of potassium permanganate with an Mn(II) salt such as manganese sulfate (under either alkaline or acidic conditions), followed by thorough drying, yields the oxidizing agent: activated MnO2. While MnO2 is insoluble in the solvents used for the reaction, the...
01:26Redox Titration: Other Oxidizing and Reducing Agents
Besides iodine, other oxidizing or reducing agents can serve as titrants in redox titrations. Common oxidizing titrants include KMnO4, cerium(IV), and K2Cr2O7. The choice of oxidizing titrants depends on factors like stability, cost, analyte strength, and reaction rate between the analyte and titrant. KMnO4 is a strong oxidizing titrant that reduces from Mn(VII) to Mn(II) in a highly acidic solution, simultaneously oxidizing the analyte to a higher oxidation state. In this case, KMnO4 acts as a...
01:27Microbial Leaching
Microbial leaching, also known as bioleaching, is an environmentally favorable method for extracting metals from low-grade ores using specific microorganisms. This biotechnological approach is particularly valuable for mining operations targeting copper, gold, and uranium, where traditional extraction methods may be economically or environmentally impractical.Copper Leaching and Microbial CatalysisIn copper bioleaching, crushed ore is arranged into heaps and irrigated with a dilute sulfuric...
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...
01:28Microbial 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...