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Reductive dissolution of Fe(III) oxides by Pseudomonas sp. 200
R G Arnold1, T J DiChristina, M R Hoffmann
1Environmental Engineering Science, W. M. Keck Laboratories 138-78, California Institute of Technology, Pasadena, California 91125.
Biotechnology and Bioengineering
|October 20, 1988
Summary
This study reveals that nitrilotriacetic acid (NTA) significantly enhances microbial iron oxide dissolution by Pseudomonassp. 200. NTA acts as a bridging ligand, increasing mineral dissolution rates up to 20-fold.
Area of Science:
- Microbiology
- Geochemistry
- Environmental Science
Background:
- Microbial reductive dissolution of iron (III) oxides is a key process in biogeochemical cycling.
- Understanding the factors controlling these dissolution rates is crucial for environmental remediation and resource recovery.
Purpose of the Study:
- To investigate the kinetics and mechanism of Fe(III) oxide reductive dissolution by Pseudomonassp. 200.
- To determine the role of nitrilotriacetic acid (NTA) in enhancing microbial iron oxide dissolution.
Main Methods:
- Pure, batch cultures of Pseudomonassp. 200 were used to examine hematite and goethite dissolution.
- Kinetic experiments were conducted to assess the influence of mineral surface area, ligand concentration (NTA), and cell number.
- A kinetic expression was developed to relate iron-reduction rate to NTA and Fe(III) concentrations.
Main Results:
- Hematite dissolution kinetics were primarily controlled by mineral surface area, ligand concentration, and cell number.
- Nitrilotriacetic acid (NTA) addition resulted in saturation kinetics and a 20-fold increase in the microbial dissolution rate of hematite.
- Cell-mineral contact was essential for the reductive dissolution of goethite.
Conclusions:
- Nitrilotriacetic acid significantly enhances microbial reductive dissolution of iron (III) oxides by Pseudomonassp. 200.
- NTA may act as a bridging ligand or accelerate Fe(II) release, facilitating faster mineral dissolution.
- Cell-mineral contact is a critical factor for microbial iron oxide dissolution, particularly for goethite.
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