Hyperosmotic response of streptococcus mutans: from microscopic physiology to transcriptomic profile

BMC Microbiology

Xin Xu²  Yi Yang¹  Renke Wang²  Yuqing Li²  Mingyun Li²  Lei Cheng²  Keke Zhang²  Xuedong Zhou²  Yulong Niu¹  Chengcheng Liu² 

[1]Key Lab of Bio-resources and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China

[2]State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China

关键词: Dental plaque;    Environmental fitness;    Biofilm dispersal;    Transcriptional profile;    Hyperosmotic condition;    Streptococcus mutans;   

Others  :  1142501
DOI  :  10.1186/1471-2180-13-275

 received in 2013-07-16, accepted in 2013-11-26,  发布年份 2013

【 摘 要 】

Background

Oral streptococci metabolize carbohydrate to produce organic acids, which not only decrease the environmental pH, but also increase osmolality of dental plaque fluid due to tooth demineralization and consequent calcium and phosphate accumulation. Despite these unfavorable environmental changes, the bacteria continue to thrive. The aim of this study was to obtain a global view on strategies taken by Streptococcus mutans to deal with physiologically relevant elevated osmolality, and perseveres within a cariogenic dental plaque.

Results

We investigated phenotypic change of S. mutans biofilm upon hyperosmotic challenge. We found that the hyperosmotic condition was able to initiate S. mutans biofilm dispersal by reducing both microbial content and extracellular polysaccharides matrix. We then used whole-genome microarray with quantitative RT-PCR validation to systemically investigate the underlying molecular machineries of this bacterium in response to the hyperosmotic stimuli. Among those identified 40 deferentially regulated genes, down-regulation of gtfB and comC were believed to be responsible for the observed biofilm dispersal. Further analysis of microarray data showed significant up-regulation of genes and pathways involved in carbohydrate metabolism. Specific genes involved in heat shock response and acid tolerance were also upregulated, indicating potential cross-talk between hyperosmotic and other environmental stress.

Conclusions

Hyperosmotic condition induces significant stress response on S. mutans at both phenotypic and transcriptomic levels. In the meantime, it may take full advantage of these environmental stimuli to better fit the fluctuating environments within oral cavity, and thus emerges as numeric-predominant bacterium under cariogenic conditions.

【 授权许可】

   
2013 Liu et al.; licensee BioMed Central Ltd.

【 图 表 】

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