Bacteriophage deoxyribonucleic acid-induced mutation of Streptococcus mutans

Area of Science:

• Microbiology
• Molecular Biology
• Dental Research

Background:

• Streptococcus mutans is a primary agent of dental caries.
• The role of prophage in the virulence of S. mutans PK 1 was previously uncharacterized.

Purpose of the Study:

• To investigate the presence and role of prophage in Streptococcus mutans PK 1.
• To determine if prophage influences the cariogenic and adhesive properties of S. mutans PK 1.

Main Methods:

• Electron microscopy was used to visualize phage particles.
• Mitomycin C was employed to induce prophage.
• Mutant strains were transformed using isolated phages and phage DNA.

Main Results:

• Prophage particles were detected in the wild-type S. mutans PK 1 strain.
• A mutant strain lacking adhesive properties and reduced polysaccharide synthesis did not exhibit detectable prophage.
• Transformation of the mutant strain with phages or phage DNA restored adhesive nature and cariogenic characteristics.
• All transformants acquired the ability to produce ammonia from arginine, a novel trait.

Conclusions:

• Prophage is essential for the characteristic adhesive nature and cariogenicity of Streptococcus mutans PK 1.
• The genetic material of the prophage confers new metabolic capabilities, such as ammonia production from arginine, upon transformation.