There are three processes by which genetic material of one bacteria can pass to the other bacteria and these processes are transformation, conjugation, and transduction.
In transduction bacteriophage( virus that infects bacteria) is responsible for the transfer of genetic material of one bacteria to another bacteria. When a virus infects one bacteria its genetic material divides with the bacterial DNA and sometime during making new phage particles part of bacteria DNA gets packed in viral capsid.
When that virus infects another bacteria the genetic material of other bacteria gets incorporated in its host genome and this process is called transduction.
