EFFECTS OF BICARBONATE ON GROWTH OF PASTEURELLA PESTIS. 3. REPLACEMENT OF BICARBONATE BY PYRIMIDINES

Area of Science:

• Microbiology
• Bacteriology
• Biochemistry

Background:

• Pasteurella pestis virulence is affected by culture conditions.
• Carbon dioxide metabolism plays a role in bacterial growth and virulence.

Purpose of the Study:

• To investigate the effects of bicarbonate and its metabolic products on Pasteurella pestis growth and virulence.
• To explore the role of pyrimidine synthesis in maintaining P. pestis virulence.

Main Methods:

• Culturing virulent Pasteurella pestis at 37°C with aeration.
• Replacing bicarbonate with pyrimidines (orotic acid, cytosine, uracil, citrulline) in the growth medium.
• Assessing bacterial growth and retention of virulence.

Main Results:

• Orotic acid effectively replaced bicarbonate, stimulating growth and maintaining virulence.
• Cytosine, uracil, and citrulline also supported virulence but with less pronounced growth effects.
• Bicarbonate or orotic acid supplementation prevented virulence loss in aerated cultures.

Conclusions:

• Impaired pyrimidine synthesis, potentially due to carbamyl phosphate deficiency, is linked to P. pestis virulence loss.
• Loss of metabolically produced carbon dioxide may exacerbate carbamyl phosphate deficiency in aerated cultures.