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Freezing-warming Method for Transformaton of E. coli
Comparison among the transformation efficiency (colony forming unit/μg DNA) of the freezing-warming method, calcium chloride method and TSS method
Comparison among the transformation efficiency (colony forming unit/μg DNA) of the freezing-warming method, calcium chloride method and TSS method

Author:Chang-Sheng Wang and Ren-Mon Liao

Abstract:

We report a freezing-warming method for transformation of E. coli. In this method, plasmid DNA were mixed with 100 µl ice cold competent cells, freezing treated in liquid nitrogen for 5 min followed with heat treatment at 37℃ for 5 min, then directly spread onto the selective agar plate pre-warmed to 37℃ and cultured for 16-18 hr. Addition of recovery culture at 37℃ for 30 min before plating increased transformation efficiency several folds, however more time was required. The advantage of this new transformation method is time-saving. In general, a transformation efficiency up to 8.7 Í 106 colony forming units/µg DNA can be achieved by this method within 15 min and it is significantly faster than most of the reported methods that usually require 75-90 min.

Key words:Transformation, Freezing-warming method, E. coli

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Journal of
Taiwan Agricultural Research
Vol. 73, No.1 (2024) ISSN: 2790-086X Vol. 73, No.1 (2024)
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