MS临床株变链素抑菌活性检测和相关基因的PCR分析

Determination of mutacin activity and detection of mutacin structural genes in MS isolates by PCR analysis

目的:对MS临床株产生变链素的抑菌活性进行检测并分析已知变链素的结构基因在MS临床株中的分布情况,为筛选新变链素产生株提供信息。方法:选择20例成年个体的100株MS,首先用平板法检测MS菌株产生的变链素对10个指示株产生的抑菌环大小和抑菌谱的多少,再用PCR方法扩增3种不同变链素结构基因的序列,观察有无扩增。结果:所有的实验株(100%)均可产生抑制6～8个指示株的变链素,抑菌环和抑菌谱在不同个体之间变异。PCR扩增mutAI基因的阳性率为26%,对mutAII和mutAIII的PCR扩增均未见扩增产物。结论:MS临床株均可产生变链素,但已知变链素的结构基因在其中的分布率低,提示可能有未知变链素的存在。

Objective：To determine mutacin activity and to detect mutacin structural genes in MS isolates.Methods：First,the mutacin activities of 100 MS isolates from 20 individuals were tested against 10 indicator strains by the stab method,then mutA gene coding for mutacins-known was detected by PCR.Results：The mutacins were produced by all of the strains against 6 to 8 indicator strains.Results showed significant variations in the mutacin production profiles and the inhibitory spectra among individuals.Homology to the mutA gene coding for mutacin I was detected in 26 clinical isolate strains,PCR screening primers mutAII,mutAIII did not yield amplicons in any of the strains tested.Conclusion：The low frequency of detection of mutA suggests that there is a high diversity in the genetic determinants needed for production of mutacin-like substances.