Ditiatkin S Ia, Il'iashenko B N
Genetika. 1979;15(2):220-5.
Plasmid DNA transformation efficiency depends on three essential factors: 1) the optimal regime of the recipients freezing-thawing; 2) the period of the recipients competence preservation; 3) individual sensitivity of microorganisms to freezing-thawing. It is demonstrated that plasmid DNA pMB9 activity indices are of maximal value during freezing at -70 degrees C or -196 degrees C and thawing at 42 degrees C. The short period of the competence, about 15 seconds, determines the rate of its infection. In this case it was achieved by mutual freezing-thawing of bacteria and DNA pMB9. The optimal yield of transformants is obtained in the following conditions: the concentration of bacteria - 1 - 5.10(9) cells/ml, the concentration of DNA pMB9 - 0.05--0.5 mcg/ml in the reaction mixture containing 0.5--1% of bactopeptone ("Spofa") and at pH 7.4--7.6.
质粒DNA转化效率取决于三个关键因素：1）受体菌冻融的最佳条件；2）受体菌感受态的保存时间；3）微生物对冻融的个体敏感性。结果表明，质粒DNA pMB9的活性指标在-70℃或-196℃冷冻以及42℃解冻时达到最大值。感受态的短时间（约15秒）决定了其感染率。在这种情况下，通过细菌与DNA pMB9的相互冻融实现。在以下条件下可获得最佳的转化子产量：细菌浓度为1 - 5×10⁹个细胞/毫升，在含有0.5 - 1%细菌蛋白胨（“斯波法”）且pH值为7.4 - 7.6的反应混合物中，DNA pMB9的浓度为0.05 - 0.5微克/毫升。
