Hyperosmotic response of streptococcus mutans: from microscopic physiology to transcriptomic profile
Chengcheng Liu, Yulong Niu, Xuedong Zhou
1State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China. nixux1982@hotmail.com.
BMC Microbiology
|December 3, 2013
Summary
Oral bacteria Streptococcus mutans adapt to high salt conditions by altering their biofilm structure and metabolism. This stress response helps them survive and thrive in the acidic oral environment, contributing to tooth decay.
Area of Science:
- Microbiology
- Oral Biology
- Molecular Biology
Background:
- Oral streptococci, including Streptococcus mutans, produce organic acids from carbohydrate metabolism, lowering pH and increasing osmolality in dental plaque.
- Tooth demineralization leads to calcium and phosphate accumulation, further increasing plaque fluid osmolality.
- Despite these harsh conditions, oral streptococci persist, necessitating an understanding of their survival strategies.
Purpose of the Study:
- To investigate the phenotypic and molecular strategies employed by Streptococcus mutans in response to hyperosmotic stress.
- To gain a global perspective on how this bacterium adapts to the osmotically challenging environment of cariogenic dental plaque.
Main Methods:
- Phenotypic analysis of Streptococcus mutans biofilm under hyperosmotic conditions.
- Whole-genome microarray analysis to identify differentially regulated genes.
- Quantitative RT-PCR validation of gene expression changes.
Main Results:
- Hyperosmotic stress induced S. mutans biofilm dispersal by reducing microbial content and extracellular polysaccharides.
- Down-regulation of gtfB and comC genes was associated with biofilm dispersal.
- Significant up-regulation of genes involved in carbohydrate metabolism, heat shock response, and acid tolerance was observed, suggesting cross-talk between stress responses.
Conclusions:
- Hyperosmotic conditions trigger significant phenotypic and transcriptomic stress responses in S. mutans.
- These adaptations allow S. mutans to leverage environmental stimuli for survival and dominance in the fluctuating oral cavity.
- S. mutans' ability to adapt to osmotic stress contributes to its prevalence under cariogenic conditions.
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