Final answer:
The initiation of phage reproduction in a lysogenized culture due to environmental stressors triggering a switch from the lysogenic to lytic cycle is known as induction, not repression or enhancement.
Step-by-step explanation:
The process by which phage reproduction is initiated in a lysogenized culture is known as induction. In the context of a temperate bacteriophage's life cycle, there are two main pathways: the lytic cycle and the lysogenic cycle. During the lysogenic cycle, the phage's DNA is incorporated into the host's genome becoming a prophage. However, certain environmental stressors, such as starvation or exposure to toxic chemicals, may trigger the prophage to become active, excise from the bacterial chromosome, and initiate the lytic cycle. This switch from lysogeny to lytic reproduction is termed induction or the induction process. It contrasts with repression, where phage gene expression is inhibited to maintain the lysogenic state.
Understanding these cycles is crucial for comprehending how phages replicate and how they can impact bacterial behavior through processes such as lysogenic conversion, where bacteria gain new characteristics from the incorporated phage DNA, like toxin production resulting in increased virulence.