细菌质粒的消除

利用化学消除剂或改变生长条件可以消除细菌中的质粒，除宿主菌的特性及其所含质粒分子量大小之外，消除率还与消除剂浓度，作用时间有关，嵌合染料适用于消除大肠杆菌中的质粒，十二烷基硫酸钠对具有性纤毛的细菌作用效果较好，适当提高培养温度可消除一些细菌中的质粒，胸腺嘧啶限量法仅适用于其营养缺陷菌株的质粒消除，利用原生质体的形成与再生及反复冻融菌体均可消除细菌中的质粒。

PLASMID CURING IN BACTERIA

Plasmids in bacteria can be cured by using chemical curing agents or changing growth conditions. Besides the character of host strains and the molecular weight of the plasmid, the efficiency of curing was also related to the concentrations of curing agents and the time of treatment. Intercalating dyes were suitable for curing the plasmids in E.coli while sodium dodecyl sulfate can gain good results in the bacteria which have sex pili on their cell surface. Elevated growth temperature has been successfully used in curing plasmids of some strains. Thymine limitation can only be used to cure thymine-requiring auxotrophs. The elimination of plasmids in certain bacteria can occur during the formation and regeneration of protoplast and repeatly freezing and thawing of cells.