生长期和pH值对格氏链球菌自溶酶atlS基因表达的影响

Effects of growth stages and pH value on the expression of autolytic enzyme atlS gene of Streptococcus gordonii

目的检测格氏链球菌自溶酶atlS基因在不同生长期和p H值条件下表达水平的差异,分析生长期和p H值对格氏链球菌atlS基因表达的影响,进而分析调控格氏链球菌atlS基因表达的因素。方法收集不同生长期(对数生长早期、对数生长中期、对数生长晚期、稳定期)及不同p H值(7.0和5.5)条件下培养的格氏链球菌野生株ATCC35105细胞,常规方法提取总RNA。采用荧光定量聚合酶链反应(FQ-PCR)法,以细菌的16S r RNA为内参照,分别测定atlS基因mRNA的相对表达量,比较格氏链球菌在不同生长期及p H值下atlS mRNA的表达水平。结果 FQPCR结果发现,atlS基因表达从对数生长早期到稳定期逐步升高,中性条件下atlS基因表达高于酸性条件,其差异有统计学意义(P<0.05)。结论格氏链球菌atlS基因表达受细菌生长期和p H值的影响。

Objective This study aimed to detect the difference in the expression levels of autolysin atlS gene of Strepto- coccus gordonii （S. gordonii） at different growth stages and pH values, as well as to analyze the factors regulating atlS gene expression in S. gordonii. Methods S. gordonii wild strains （ATCC 35105） were collected at different growth stages （early exponential phase, mid-exponential phase, late exponential stage, and platform., stage） and pH values （pH 7 and pH 5.5）, and total RNA was extracted by using a conventional method. Fluorescence quantitative polymerase chain reaction （FQ-PCR） was used to measure the relative mRNA expression of atlS gene, with bacterial 16S rRNA as internal reference, for a com- parison of the mRNA levels of atlS gene expression in S, gordonii at different growth stages and pH values. Results FQ-PCR results showed that atlS gene expression increased with gradually increasing growth stage under neutral conditions and was higher than that under acidic conditions （P〈0.05）. Conclusion The atlS gene expression in S. gordonii is influenced by growth stage and pH value factors.