Intact Genomics (ig®) Electrocompetent BL21(DE3)pLysS electrocompetent cells are suitable for transformation and routine protein expression. The pLysS plasmid produces T7 lysozyme that reduces base level expression of the gene of interest, subsequently allowing for tighter control of expression and is therefore suitable for expression of toxic genes.  BL21(DE3)pLysS electrocompetent cells also carry the chloramphenicol resistance gene.

Transformation efficiency is tested by using the pUC19 control DNA supplied with the kit and using the protocol given below. Transformation efficiency should be ?1 x 1010 CFU/µg pUC19 DNA. Untransformed cells are tested for appropriate antibiotic sensitivity.