there are a group of viruses called bacteriophages. These bacteriophages inject their viral dna into the host cell of bacteria. The viral dna then becomes incorporated into the chromosome of the bacterium. Thus the viral dna forms part of the bacterial chromosome and will be copied to all daughter cells. Though this viral dna will become active again at low frequency’s.
The transfer of bacterial dna by phages from an infected bacterium to another bacterium.