Name two stationary-phase adaptations bacteria may employ to survive stress.

• A. Activation of the stringent response (ppGpp) and increased production of stress proteins; some cells form VBNC or spores
• B. Rapid exponential growth
• C. Immediate lysis due to toxins
• D. Loss of membranes

Answer: (A)

During stationary phase, nutrients are scarce and stress accumulates, so bacteria switch into survival mode. The most effective adaptations include the stringent response, driven by the alarmone ppGpp, which reprograms transcription to conserve energy and redirect resources toward maintenance and stress resistance. Alongside this, cells increase production of stress-related proteins, such as molecular chaperones and proteases, to keep proteins functional and repair damaged ones.

Some bacteria also enter durable survival states like viable-but-nonculturable (VBNC) cells, which lower their metabolic activity while remaining alive, or form endospores in species capable of doing so. These strategies greatly enhance long-term survival under harsh conditions.

Rapid exponential growth happens when conditions are favorable, not during stationary-phase stress. Immediate lysis due to toxins would destroy cells, and loss of membranes is detrimental to viability, not an adaptive survival strategy.