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Gallium toxicity and adaptation in Pseudomonas fluorescens
A al-Aoukaty1, V D Appanna, H Falter
1Department of Chemistry and Biochemistry, Laurentian University Sudbury, Ontario, Canada.
FEMS Microbiology Letters
|May 1, 1992
Summary
Pseudomonas fluorescens exhibits a lag phase when exposed to gallium (III), which is mitigated by iron (III) or adapted cells. Gallium stress induces specific protein synthesis in this bacterium.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Gallium (III) is a trivalent metal that can impact bacterial physiology.
- Pseudomonas fluorescens is a common soil bacterium with known metabolic capabilities.
Purpose of the Study:
- To investigate the effects of gallium (III) on the growth and protein expression of Pseudomonas fluorescens ATCC 13525.
- To determine the role of iron (III) in mitigating gallium toxicity.
Main Methods:
- Culturing Pseudomonas fluorescens in defined citrate medium with and without gallium (III) and iron (III).
- Monitoring bacterial growth, metal uptake, and secretion using X-ray fluorescence spectroscopy.
- Analyzing cytoplasmic protein profiles using electrophoretic methods.
Main Results:
- Gallium (III) induced a 40-hour lag phase in Pseudomonas fluorescens, which was abolished by iron (III) or gallium-adapted cells.
- Iron (III) reversed gallium's inhibitory effect on growth in phosphate-deficient medium.
- Gallium stress led to the induction of specific polypeptides (89, 50, 39, 26, and 12 kDa) in Pseudomonas fluorescens.
Conclusions:
- Iron (III) plays a crucial role in alleviating gallium (III) toxicity in Pseudomonas fluorescens.
- Gallium (III) exposure triggers significant changes in the bacterium's proteome, indicating a stress response mechanism.