Final answer:
Lysogenic phages increase the pathogenicity of a bacterium by incorporating their DNA into the host genome, which can grant new harmful properties to the bacterium. Lytic phages, in contrast, lead to the destruction of the host cell without integrating their DNA.
Step-by-step explanation:
Bacteriophages that can increase the pathogenicity of a bacterium are typically lysogenic phages. These phages can integrate their DNA into the host bacterial genome, a state known as a prophage, during the lysogenic cycle. While in this state, the bacteriophage DNA can confer new characteristics to the bacterium, such as toxin production or resistance to the immune system, resulting in increased pathogenicity. The DNA from the lysogenic phage can be excised in response to certain environmental stressors, re-entering the lytic cycle, which leads to the production of new phages and the lysis of the host cell.
In contrast, lytic phages prioritize the replication and release of new phage particles over integration, resulting in the rapid destruction of the host cell. The lytic cycle does not typically contribute to the bacterium's pathogenicity other than causing cell death.