IMPROVEMENT OF A SIMPLE AND EFFECTIVE TRANSFORMATION ASSAY FOR E COLIBOUSSOUAR NACEURAbstract Searching for efficient means by which bacteria uptake plasmid DNA is of a great practical importance in molecular biology and genetic engineering. We have described in this study five assays for preparing transformants E. coli cells (strain JM109) which are extremely efficient for plasmid uptake that typically yielded transformation efficiencies between 7.2Ã105â1.9Ã107 colony-forming units per microgram (CFU/ïg) of plasmid DNA. Assay 05 with transformation efficiency 1.9Ã107 CFU/μg is the simplest and most effective. This assay was considered easy if compared with the original rapid colony transformation protocol described by Hanahan et al., 1991, in which they used transformation buffer (TFB) as transformation solution and the super-optimal broth with catabolite repression (SOC) media, these two are more complex if compared with CaCl2 solution and Luria Bertani (LB) media. One more point in favor of this protocol is its low time consumption. Transformation efficiency between 106 and 107 is not optimal but it is above average for molecular experiments. Therefore, it is possible that these assays may be widely applicable for bacterial transformations with plasmids and can be used as an inexpensive and reliable alternative to existing methods. |