Regulation of urease gene of Actinomyces naeslundii in biofilms in response to environmental factors
Regulation of urease gene of Actinomyces naeslundii in biofilms in response to environmental factors
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DOI：
10.1111/j.1574-6968.2007.00959.x
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发表时间：
2008-01-01
影响因子：
2.1
通讯作者：
Zhou, Xuedong
中科院分区：
文献类型：
--
作者：
Liu, Yaling;Hu, Tao;Zhou, Xuedong
口腔细菌脲酶对尿素的代谢对口腔生物膜pH稳态和口腔微生物生态有着深远的影响，而内氏放线菌是口腔中重要的尿素分解微生物。为了深入了解不同环境条件下在生物膜中生长的内氏放线菌细胞中脲酶基因表达的调节，在体外生物膜中检查了内氏放线菌 ATCC12104 的行为。将菌株培养在恒化生物膜反应器中，在准稳态下，测定生物膜细胞的脲酶活性，并用Taqman定量PCR检测ureC基因的转录。通过改变培养物液相的环境pH、稀释率、碳水化合物和氮的可用性来检查环境变化对脲酶表达的影响。结果表明，中性pH、快速稀释速率、增加培养基中碳水化合物供应或低氮供应的条件均导致生物膜细胞中脲酶活性增强。但仅观察到低氮利用率和快速稀释率会导致 ureC mRNA 水平增加。这表明氮的有效性和稀释率可以通过调节ureC基因转录来影响内氏放线菌的脲酶活性。
The metabolism of urea by urease enzymes of oral bacteria has a profound influence on oral biofilm pH homeostasis and oral microbial ecology, and Actinomyces naeslundii is an important ureolytic organism in the oral cavity. To gain an insight into the regulation of urease gene expression in cells of A. naeslundii growing in biofilms under different environmental conditions, the behavior of A. naeslundii ATCC12104 was examined in in vitro biofilms. The strain was grown in a chemostat biofilm reactor, and at a quasi-steady state, the urease activity of biofilm cells was measured and transcription of ureC gene was detected with Taqman quantitative PCR. The effect of environmental changes on urease expression was examined by varying the environmental pH, dilution rate, carbohydrate and nitrogen availability of the fluid phase of the culture. The results showed that the conditions of neutral pH, fast dilution rate, increased carbohydrate supply or low nitrogen supply in the medium all resulted in enhancement of urease activity in biofilm cells. But only low nitrogen availability and a fast dilution rate were observed to lead to an increase in ureC mRNA levels. This suggests that nitrogen availability and dilution rate can influence the urease activity of A. naeslundii by modulating ureC gene transcription.