Conjugation in Gram-positive bacteria
Most bacteria contain one or more autonomously replicating units called plasmids, which have a modular structure. Besides an essential DNA replication module, many plasmids contain a conjugation module containing all the genes required for transfer of the plasmid from a donor to a recipient cell via a connecting pore. These plasmids, named conjugative plasmids, often contain toxin, virulence and/or antibiotic resistance genes. Conjugation is the main horizontal gene transfer route responsible for the spread of these genes.