Pefeifer M, Pöhlmann C, Betcke A, Kurth M, Liebscher D H
Z Allg Mikrobiol. 1980;20(4):271-81.
This paper presents further parameters influencing the competence, the process of DNA uptake and the efficiency of plating of CaC12-treated E. coli D12 strains. We have found that the process of DNA uptake depends not only on the treatment of bacteria with a certain CaCl2-concentration but is also influenced considerably by a shift-down of the CaCl2-concentration in the reaction mixture. The pH of the growth media and of the reaction mixture plays an important role in maintaining of optimal transfection. The efficiency of plating is influenced by the thickness of the top layer and the concentration of bacteria on the plate. Without genetic variation of the strains, by only varying the mentioned factors we could improve the efficiency of CaCl2 transfection at about two orders of magnitude to a maximum of 6 X 105 pfu/microgram DNA.
本文介绍了影响氯化钙处理的大肠杆菌D12菌株的感受态、DNA摄取过程及平板接种效率的其他参数。我们发现，DNA摄取过程不仅取决于用一定浓度氯化钙处理细菌，还受到反应混合物中氯化钙浓度降低的显著影响。生长培养基和反应混合物的pH值在维持最佳转染中起重要作用。平板接种效率受顶层厚度和平板上细菌浓度的影响。在菌株无基因变异的情况下，仅通过改变上述因素，我们就能将氯化钙转染效率提高约两个数量级，最高可达6×10⁵ 噬菌斑形成单位/微克DNA。
