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CARBON DIOXIDE FIXATION IN BACILLUS ANTHRACIS
1U.S. Army Chemical Corps, Biological Laboratories, Fort Detrick, Frederick, Maryland.
Journal of Bacteriology
|February 1, 1963
Summary
Bacillus anthracis requires high carbon dioxide (CO2) levels for capsule production. CO2 is rapidly fixed into aspartic acid, suggesting a direct pathway for CO2 assimilation in this bacterium.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Virulent Bacillus anthracis strains necessitate elevated carbon dioxide (CO2) concentrations for capsular material (glutamyl polypeptide) production.
- Avirulent strains exhibit variable polypeptide production, with some producing it in ambient air.
Purpose of the Study:
- To investigate the mechanism of carbon dioxide fixation in Bacillus anthracis.
- To elucidate the role of CO2 concentration in the synthesis of glutamyl polypeptide.
Main Methods:
- Utilized C14-labeled carbon dioxide (C14O2) to trace CO2 fixation pathways.
- Analyzed labeled intermediates in bacterial extracts using chromatography.
- Investigated the stability of C14 incorporation by flushing with unlabeled CO2 (C12O2).
Main Results:
- C14O2 fixation resulted in labeling of aspartic acid, glycine, glutamic acid, succinic acid, and an unidentified organic acid.
- Aspartic acid was rapidly labeled (<30 seconds) and C14 was displaced by C12O2, indicating its role as a primary fixation product.
- A direct carbon pathway from CO2 to aspartic acid (oxaloacetic acid), then to glutamic acid and glutamyl polypeptide is suggested.
Conclusions:
- Aspartic acid is a key intermediate in the primary CO2 fixation process in Bacillus anthracis.
- The findings suggest a direct metabolic route for carbon dioxide assimilation linked to virulence factor production.