Question

In which phase would you expect to observe the most endospores in a Bacillus cell culture?

a) Lag phase
b) Log phase
c) Stationary phase
d) Death phase

Answer 1

You would observe the most endospores in a Bacillus cell culture during the stationary phase when nutrient depletion and waste accumulation trigger sporulation. Penicillin is most effective during the log phase when Bacillus cells are actively dividing and building cell walls.

Step-by-step explanation:

In which phase would you expect to observe the most endospores in a Bacillus cell culture? The most endospores would be observed during the stationary phase. During the stationary phase, Bacillus cells switch to a survival mode of metabolism. As growth slows, cells undergo sporulation and produce endospores as a defensive strategy due to the depletion of nutrients and the accumulation of toxic waste. This is also the phase where secondary metabolites and virulence factors are often produced.

The most effective phase for penicillin, an antibiotic that inhibits cell-wall synthesis, would be during the log phase. In the log phase, Bacillus cells are actively dividing and synthesising cell walls, making them most susceptible to penicillin. In contrast, in the stationary phase, the synthesis of materials like peptidoglycans that make up the cell wall slows down, reducing the effectiveness of such antibiotics.