中文摘要：

目的从变异链球菌临床株中分离纯化变链素,为进一步从分子水平研究变链素奠定基础。方法通过抑菌活性检测,从变异链球菌临床株中选择出抑菌活性较强的菌株。用氯仿抽提法从该菌株培养液中粗提变链素,经固相萃取和反相高效液相色谱（RP-HPLC）对粗提物进行纯化。结果获得变链素活性较强的菌株1G。从其200 mL液体培养基中粗提出变链素约15μg,经固相萃取柱洗脱,再经过RP-HPLC的2次纯化,得到有抑菌活性的成分,此为纯化的变链素。结论变链素相对分子质量小,分离提纯步骤复杂,本实验得到纯化的变链素,为下一步研究变链素的氨基酸序列和基因序列奠定了基础。

英文摘要：

Objective To purify mutacin produced from isolated Streptococcus mutans（S.mutans） strains in order to,contribute to molecular biological research of mutacin.Methods The antibacterial activity of 80 isolated strains was tested by the stab culture technique against Streptococcus oralis ATCC 10557.The mutacin produced by strain 1G,was initially purified by solid-phase extraction（SPE） after crude extraction by chloroform.And then the active substances were purified by twice reversed-phase high performance liquid chromatography（RP-HPLC）.The purified target peptide（mutacin） was collected and freeze-dried for further study.Results The greatest active strain of these S.mutans isolates,the strain 1G was obtained.Roughly 15 μg crude mutacin was extracted from 200 mL liquid medium of this strain 1G.The purified mutacin through SPE and twice RP-HPLC was obtained.Conclusion It was much complex to separate and purify mutacin due to its small molecular mass,and extracting and purifying of mutacin may make an important contribution to the further research of mutacin.