THE EFFECT OF FORMALDEHYDE ON PNEUMOCOCCI

Area of Science:

• Microbiology
• Immunology
• Biochemistry

Background:

• Formaldehyde is commonly used to preserve bacterial cells.
• Pneumococci possess autolytic enzymes that influence cell integrity and staining.
• The Gram stain reaction is a critical characteristic for bacterial identification.

Purpose of the Study:

• To investigate the effect of formaldehyde concentration on pneumococcal autolysis.
• To determine the role of autolytic enzymes in formaldehyde-treated pneumococci.
• To evaluate the immunogenicity of formaldehyde-treated pneumococci as type-specific antigens.

Main Methods:

• Treatment of pneumococci with varying formaldehyde concentrations.
• Washing and resuspension of formaldehyde-treated pneumococci in physiological solutions.
• Assessment of morphological and staining characteristics (Gram stain).
• Evaluation of antibody elicitation in rabbits using treated pneumococci.

Main Results:

• Low formaldehyde concentrations enhanced autolysis; high concentrations inhibited it, preserving cell morphology and Gram-positive staining.
• Washed, formaldehyde-treated pneumococci, when reactivated, became Gram-negative due to autolytic enzyme activity.
• Formolized pneumococci retaining Gram-positive character were effective type-specific antigens, while Gram-negative ones were not.

Conclusions:

• Formaldehyde concentration critically controls pneumococcal autolysis and Gram staining.
• The autolytic enzyme's activity is key to the Gram-negative conversion and loss of antigenicity.
• Stabilized, Gram-positive formolized pneumococci are valuable for preparing potent type-specific antigens.