Overview
A Successful transformation of E.coli with a cDNA library or ligated plasmid DNA is dependant on the efficiency of transformation. Electroporation is the method of choice to achieve high efficiencies of up to 109 colonies per ug of plasmid.
Tips
Transformation efficiency should be between 108 to 109 colony per ug of supercoiled plasmid DNA.
If cuvette arcs with a loud pop during electroporation this means that the cells or the DNA used for transformation contain salts. Low time constants are also indicative of the presence of salts and will results in reduced transformation efficiency. If cells alone, without addition of DNA create electric arc ,discard cells and prepare new batch. Wash cells more extensively with double distilled water and use ultrapure water to prepare 10% glycerol solution.
If DNA creates arc, reduce volume of ligation used in transformation or clean DNA by ethanol precipitation.
Ampicilin resistance does not require incubation of cells prior to plating to be effective.
Do not overgrow transformed cells plated on ampicillin medium or non transformed cells (satellites) will grow around the transformed cells.
Do not use 4 mm cuvettes for bacteria