decline phase

The decline phase, also known as the death phase, is the final stage in bacterial growth. It occurs when the rate of bacterial cell death exceeds the rate of cell growth. This typically happens when essential nutrients in the growth medium are depleted, and waste products accumulate, creating unfavorable conditions for survival. During this phase, the bacterial population decreases significantly. Some bacteria may form resistant endospores to survive unfavorable conditions, which can germinate and begin growing again when conditions improve. The decline phase follows the lag, log, and stationary phases of bacterial growth.12