Abstract:

[Abstract] Objective  To study the effect of inactivation of high temperature requirement A (htrA) or caseinolytic protease P (clpP) on the iron metabolism of Streptococcus mutans.Methods  The nephelometer method was used to measure the absorbance of iron-limited defined medium in which Streptococcus mutans standard strains or htrA, clpP mutant strains were cultured for 24 hours. And the absorbance of all three strains was also measured and analyzed in the iron-limited defined medium with exogenous iron added or mutant and standard strains co-cultured in proportion to 1∶1 for 24 hours. Results  Compared to the standard strains, the growth of htrA mutant strains was not significantly affected until the concentration of iron chelator increased to 0.3 mmol/L (P＜0.05). The growth of clpP mutant strains was significantly affected in medium containing 0.2 mmol/L iron chelator (P＜0.05). The growth inhibition of mutant strains showed varying degrees of reversal when added exogenous iron to the iron-limited medium or 1∶1 co-cultured with standard strains. Conclusion  htrA gene or clpP gene plays an important role in iron metabolism of Streptococcus mutans.

Key words: Streptococcus mutans, htrA gene, clpP gene, irom limitation, iron metabolism, 铁代谢