Abstract: A method of producing transformation competent bacteria, comprising the steps of: (i) transforming a bacteria that is not naturally transformation competent with a plasmid, wherein said plasmid comprises a comX gene sequence encoding a ComX protein or functional part or derivative or variant thereof under the regulatory control of a promoter which is inducible by a transcription initiator, (ii) contacting said transformed bacteria with said transcription initiator to initiate transcription of said comX gene sequence is provided. Also provided are plasmids, transformed bacteria, transformation competent bacteria, mutant bacteria and food products comprising said mutant bacteria.