When do bacteria begin to die off more quickly than they reproduce?

In the decline phase, bacteria experience a significant reduction in viability due to factors such as depleted nutrients, accumulation of waste products, and increased competition for resources. During this phase, the rate of cell death surpasses the rate of reproduction, leading to an overall decline in the bacterial population.

Understanding the context of bacterial growth phases helps clarify why this is the correct answer. In the lag phase, bacteria are adjusting to their environment and not actively reproducing, while in the log phase, they are in a growth spurt, reproducing at an exponential rate. The stationary phase occurs when the growth rate slows and stabilizes due to limited resources; here, the number of new bacteria produced balances with the number dying, rather than having more deaths than births. In contrast, the decline phase is marked by declining numbers as the detrimental conditions outweigh the bacteria's ability to reproduce, leading to a quicker die-off.