<Li> Col plasmids, which contain genes that code for bacteriocins, proteins that can kill other bacteria . </Li> <Li> Degradative plasmids, which enable the digestion of unusual substances, e.g. toluene and salicylic acid . </Li> <Li> Virulence plasmids, which turn the bacterium into a pathogen . </Li> <P> Plasmids can belong to more than one of these functional groups . </P>

Includes the attachment of viral dna to the bacterial chromosome