Transformation is one of three processes by which exogenous genetic material may be introduced into a bacterial cell , the other two being conjugation ( transfer of genetic material between two bacterial cells in direct contact ) and transduction ( injection of foreign DNA by a bacteriophage virus into the host bacterium ) .
The other two are conjugation ( transfer of genetic material between two bacterial cells in direct contact ) , and transduction ( injection of foreign DNA by a bacteriophage into the host ) .