Transformation of the rhizospheric Bacillus cereus sensu lato B25 strain using a room-temperature electrocompetent cells preparation protocol

Bacterial transformation is a crucial step in the genetic manipulation of a bacterium. However, Gram-positive bacteria are difficult to transform and consequently many different methodologies have been developed. Here, we examined the transformation efficiencies of an electroporation protocol by varying three main factors: the composition of the electroporation buffer, the strength of the electric pulse, and the composition of the recovery media. Overall, transformation efficiency was enhanced when we prepared the electrocompetent cells at room temperature instead of an ice-cold temperature. The protocol detailed in this work was demonstrated to be applicable to another B. cereus strain and two other Bacillus species, and has the potential to be applied to other undomesticated Gram-positive and/or rhizospheric bacterial strains that are difficult to transform using current methodologies.