Streptococcus mutans Proteases Degrade Dentinal Collagen.

Area of Science:

• Microbiology
• Biochemistry
• Dental Research

Background:

• Streptococcus mutans is a primary cariogenic bacterium.
• Collagen is a major structural protein in teeth and connective tissues.
• Understanding S. mutans's collagenolytic activity is crucial for caries research.

Purpose of the Study:

• To investigate the collagen-degrading capabilities of S. mutans whole cells and its fractions.
• To determine the influence of S. mutans growth phase on collagen degradation.
• To identify the specific S. mutans components responsible for collagen breakdown.

Main Methods:

• Incubation of type I collagen gels and demineralized dentin slabs with S. mutans cultures (overnight and newly inoculated) and its fractions (intracellular proteins, supernatant, membranes).
• Quantification of hydroxyproline release as a marker of collagen degradation.
• Microscopic analysis of structural changes in collagen and dentin samples.

Main Results:

• Supernatant fractions showed the highest type I collagen degradation, followed by intracellular components and overnight cultures.
• Overnight S. mutans cultures exhibited the highest dentinal collagen degradation, followed by supernatant and intracellular components.
• Newly inoculated cultures showed significantly lower degradation compared to overnight cultures; bacterial membranes showed no degradation.
• Structural damage to collagen and dentin was observed with S. mutans cultures, intracellular proteins, and supernatant.

Conclusions:

• S. mutans possesses intracellular and extracellular proteolytic activities capable of degrading type I and dentinal collagen.
• Collagen degradation by S. mutans is dependent on its growth phase.
• These proteolytic activities potentially contribute to the progression of dental caries.