| 摘要 |
PURPOSE:To improve the transformation efficiency of E.coli by using a competent cell-forming buffer solution containing manganese chloride, calcium chloride, potassium chloride and a compound selected from a specific group. CONSTITUTION:An E.coli strain such as Escherichia coli DH5 is cultured and the cells are collected e.g. by centrifugal separation. The collected E.coli cells are treated in ice water with a competent cell-forming buffer solution containing manganese chloride, calcium chloride, potassium chloride and one or more compounds selected from piperazine-N,N-bis(2-ethanesulfonic acid), N-(2- hydroxymethyl)piperazine N-2-ethanesulfonic acid, etc., and potassium acetate. The prepared competent cell suspension is frozen and preserved in the vapor phase of liquid nitrogen. The transformation efficiency of E.coli can be improved, in some case, 2-10 times as high as that of conventional process. |
