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Title: A comparison and optimization of methods and factors affecting the transformation of Escherichia coli
Authors: Verma, Chandra Shekhar
Lane, David P.
Chan, Weng-Tat
Gan, Samuel Ken-En
Keywords: Competent bacteria
DMSO method
Hanahan’s method
CaCl2 method
Heat shock
Issue Date: 2013
Source: Chan, W., Verma, C., Lane, D., & Gan, S. (2013). A comparison and optimization of methods and factors affecting the transformation of Escherichia coli. Bioscience Reports, 33(6), 931-937.
Series/Report no.: Bioscience Reports
Abstract: DNA manipulation routinely requires competent bacteria that can be made using one of numerous methods. To determine the best methods, we compared four commonly used chemical methods (DMSO, MgCl2–CaCl2, CaCl2 and Hanahan's methods) on frequently used Escherichia coli (E. coli) strains: DH5α, XL-1 Blue, SCS110, JM109, TOP10 and BL21-(DE3)-PLysS. Hanahan's method was found to be most effective for DH5α, XL-1 Blue and JM109 strains (P<0.05), whilst the CaCl2 method was best for SCS110, TOP10 and BL21 strains (P<0.05). The use of SOB (super optimal broth) over LB [Luria–Bertani (broth)] growth media was found to enhance the competency of XL-1 Blue (P<0.05), dampened JM109′s competency (P<0.05), and had no effect on the other strains (P>0.05). We found no significant differences between using 45 or 90 s heat shock across all the six strains (P>0.05). Through further optimization by means of concentrating the aliquots, we were able to get further increases in transformation efficiencies. Based on the optimized parameters and methods, these common laboratory E. coli strains attained high levels of TrE (transformation efficiency), thus facilitating the production of highly efficient and cost-effective competent bacteria.
ISSN: 0144-8463
DOI: 10.1042/BSR20130098
Schools: School of Biological Sciences 
Rights: © 2013 The Author(s) This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC-BY) ( which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SBS Journal Articles

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