中文摘要：

目的：通过研究尿素水解对内氏放线菌的生长和耐酸能力的影响，了解尿素水解对内氏放线菌的生理作用。方法：比较内氏放线菌利用尿素或其它物质作为氮源的生长浊度；采用耐酸实验研究尿素水解与细菌耐酸能力的关系。结果：与其他口腔中常见氮源物质相比，尿素可以促进内氏放线菌生长，获得更高的A值；在临床牙菌斑能够检测到的pH4．0～7．0范围内，尿素水解可以提高内氏放线菌的耐酸性，在pH3．0，尿素水解对细菌没有保护作用。结论：尿素水解可以促进内氏放线菌生长，提高酸性环境中细菌的耐酸能力，增强细菌的生存竞争力。

英文摘要：

Objective： To study the effects of ureolysis on the proliferation and acid-resistance of Actinomyces naeslundii. Methods：The growth of Actinomyces naeslundii cultured in different nitrogen sources were measured, and the acid-resistant ability of Actinomyces naeslundii cultured in acid condition with different urea concentration was compared. Results： In contrast with other nitrogen sources, Actinomyces naeslundii could be cultured by urea and higher final A value of the bacteria was obtained;at the range of pH = 4.0 -7.0, ureolysis could increase the survival of Actinomyces naeslundii from acid killing to some extend, but at pH = 3.0, ureolysis could not protect Actinomyces naeslundii anymore. Conclusion：Ureolysis may stimulate the growth of A. naeslundii and increase the acid-resistant ability of Actinomyces naeslundii.