Construction and characterization of a recombinant ureolytic Streptococcus mutans and its use to demonstrate the relationship of urease activity to pH modulating capacity
Construction and characterization of a recombinant ureolytic Streptococcus mutans and its use to demonstrate the relationship of urease activity to pH modulating capacity
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DOI：
10.1016/s0378-1097(97)00160-2
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发表时间：
1997-06-15
影响因子：
2.1
通讯作者：
Burne, RA
中科院分区：
文献类型：
--
作者：
Clancy, A;Burne, RA
为了了解口腔微生物解脲作用在抑制龋病中的作用，我们试图构建一种重组解脲变形链球菌，并将菌斑细菌的解脲能力与pH调节能力相关联。将含有唾液链球菌57的尿素酶基因的重组菌株转化变形链球菌GS-5，得到的重组菌株AC04稳定地保持了尿素酶基因的表达。在添加50mU M外源NiCl2的培养液中，尿素酶活性最高，为0.9mU/min/mg细胞干重。重组质粒的存在或在NiCl2中的生长对变形链球菌的糖酵解能力没有明显影响。变形链球菌AC04的体外pH下降分析表明，同时代谢葡萄糖和生理相关浓度的尿素，菌斑细菌的尿素酶活性增加会导致糖酵解pH下降的深度和持续时间相应减少。这些结果证明了工程化尿素酶生产变形链球菌的可行性，并提示提高牙菌斑，特别是致龋性菌斑的解脲能力，可能有助于抵消龋病过程的进展。
To begin to understand the contribution of oral microbial ureolysis to the inhibition of dental caries, we sought to construct a recombinant, ureolytic mutans streptococcus and correlate the ureolytic capacity of plaque bacteria with pH moderating ability. Streptococcus mutans GS-5 was transformed with a plasmid containing the urease genes from Streptococcus salivarius 57.I. The recombinant strain, S. mutans AC04, stably maintained the urease genes. High levels of urease activity were detected, with a maximum specific activity of 0.9 mu mol of urea hydrolyzed/min/mg cell dry weight when the growth medium was supplemented with 50 mu M exogenous NiCl2. Harboring the recombinant plasmid, or growth in NiCl2, did not markedly affect the glycolytic capacity of S. mutans. In vitro pH drop analysis of S. mutans AC04, metabolizing glucose and physiologically relevant concentrations of urea simultaneously, demonstrated that increasing the urease activity of plaque bacteria resulted in a corresponding reduction in the depth and the duration of the glycolytic pH fall. The results demonstrate the feasibility of engineering urease producing S. mutans and suggest that enhancing the ureolytic capacity of dental plaque, particularly cariogenic plaque, may help to offset the progression of the caries process.