Effects of pH on the Properties of Membrane Vesicles Including Glucosyltransferase in Streptococcus mutans

Area of Science:

• Oral Microbiology
• Bacterial Pathogenesis
• Biochemistry

Background:

• Streptococcus mutans releases membrane vesicles (MVs) that are crucial for biofilm formation.
• Glucosyltransferases (Gtfs) on MVs mediate bacterial adhesion and glucan-dependent biofilm development on tooth surfaces.
• The influence of environmental pH on MV characteristics and their role in S. mutans biofilm formation requires further investigation.

Purpose of the Study:

• To investigate the characteristics of MVs from S. mutans cultured under varying initial pH conditions (acidic and alkaline).
• To determine the effects of these MVs on biofilm formation by S. mutans and early adherent bacteria.
• To elucidate the role of pH-mediated changes in Gtfs and other components in MV-dependent biofilm development.

Main Methods:

• Extraction and characterization of MVs from S. mutans grown in media adjusted to initial pH 6.0 and 8.0 using lactic acid, acetic acid, or NaOH.
• Quantification of glucans associated with MVs under different pH conditions.
• Assessment of MV-dependent biofilm formation by S. mutans and early adherent bacteria.

Main Results:

• Initial pH significantly altered MV characteristics and their impact on biofilm formation.
• Lower Gtf levels on MVs under initial pH 6.0 conditions correlated with reduced MV-dependent biofilm formation.
• Biofilm formation under initial pH 6.0 and 8.0 (with acetic acid and NaOH) involved glucans and/or extracellular DNA expression.

Conclusions:

• Environmental pH is a critical factor modulating the pathogenic activities of S. mutans MVs in oral biofilm development.
• pH-dependent alterations in Gtf content on MVs influence their ability to promote biofilm formation.
• The findings highlight the complex interplay between pH, MVs, and biofilm matrix components in the oral cavity.