You are growing Bacillus subtilis in a bioreactor and notice that the growth rate has slowed and the pH has decreased. You suspect the bacteria are
A) using the Krebs cycle.
B) photosynthesizing.
C) fermenting.
D) dead.
E) using proteins.

Question

Quizplus · Accepted Answer

When Bacillus subtilis or any bacteria's growth rate slows and the pH decreases, it often indicates that the bacteria have switched to fermentation. Fermentation can lead to the production of acidic byproducts, which would cause the pH to drop. This is a common response when oxygen levels are low or when the primary energy sources are depleted, forcing the bacteria to ferment available sugars or other compounds to continue generating energy.

You Are Growing Bacillus Subtilis in a Bioreactor and Notice