Induction triggers — A switch from lysogeny to lysis in temperate bacteriophages is commonly induced by which of the following?

Introduction / Context:
Induction is the escape of a prophage from the lysogenic state into productive replication and cell lysis. It is classically tied to the bacterial SOS response following DNA damage.

Given Data / Assumptions:

• External stressors that damage DNA can inactivate the phage repressor system.
• Multiple modalities can cause such damage: UV light, chemicals, and various forms of irradiation.

Concept / Approach:
DNA damage activates RecA, which promotes autocleavage of certain phage repressors (e.g., lambda cI), derepressing lytic genes. Therefore, any agent that triggers the SOS pathway can induce prophage excision and lytic growth.

Step-by-Step Solution:

Verification / Alternative check:
Classic experiments show increased phage titers after exposing lysogens to UV or mitomycin C, confirming induction by diverse genotoxic stresses.

Why Other Options Are Wrong:

• Individual triggers alone are correct but incomplete; the comprehensive answer is “All of these.”

Common Pitfalls:
Assuming only UV light induces prophages; many chemical agents do so as well via the same SOS pathway.

Final Answer:
All of these