When external environment changes, Streptococcus mutans(S.mutans) can change its protein expression profile through induction or inhibition of some protein expressions to ensure survival in extreme environments. Under pH 5.5 and aerobic condition, the protein expression of S.mutans changes rapidly in a complicated manner by increasing or decreasing. The extracellular high osmotic pressure of bacteria can induce S.mutans to adjust its physiological function by activating or inactivating some special enzymes and transport proteins and changing the gene expression profile. When cultivated under high osmotic pressure, protein points of S.mutans may be increased or reduced. Adequate nutrition is very important for the growth of S.mutans. To adapt to lack of nutrition, cell size and composition of S.mutans fatty acid change with decrease in total synthesis rate of proteins. When environment temperature changes, the cells will produce denatured or abnormal proteins with increased or reduced expressions. The heat shock protein produced can induce protein peptides to refold; it can also restore the original conformation and function of proteins. Some Chinese herbal medicine extracts can significantly reduce the protein expression of S.mutans. With the application of proteomics techniques, changes in S.mutans protein expression pattern can be found under different stress states. These techniques reveal information on the mechanism of S.mutans to caries and provide a scientific basis for prevention and control of caries.
