大肠杆菌JM1O3温度敏感突变型的分离及其对质粒拷贝数的影响

The Isolation of Thermosensitive Mutants of E.coli JM103 and Their Effects on Plasmid Copy Number

通过紫外线诱变，得到32个在42℃不能生长的E.coliJM103温度敏感突变子。用PDTAIL-2△质粒转化16个突变菌株，分别得到16个不同的转化株。当从30℃转到42℃时，突变子和转化子均停止生长，而野生型则能继续生长。比较不同转化子在30℃和42℃培养条件下所携带质粒的拷贝数表明：16株中有6株质粒拷贝数提高5倍以上。本结果在DNA重组中有一定的应用价值。

32 thermosensitive mutants of E.coil JM103 which ease growing at 42℃were isolated by UV-light mutagenesis.16 out of 2 mutants were independently trans-formed by plasmid PDTAIL-2.When culture condition shifted from 30℃ to 42℃,the mu-tants and their transformants stopped growing,while the wild-type E.coil JM103 grew con-tinuously.By comparing the plasmid copy numbers beared by the bacteria at 42℃ with that at 30℃,it was showed that there were 6 out of 16 transfromants whose plasmid copy num-ber was evidently amplified by more than 5 times.The results of this work can be of value for DNA recombination practice.