When bacteria are inoculated into a new sterile nutrient broth, their numbers don't begin to increase immediately. Instead, there is a lag phase that may last for an hour or even several days. Why don't bacterial numbers increase immediately?
A. The bacteria have to establish a biofilm before their numbers can increase.
B. There are not enough nutrients for the bacteria to grow, and growth is delayed until there are some dead cells to cannibalize.
C. The medium contains inhibitors that prohibit rapid growth of the bacteria, and these must be inactivated before bacterial numbers will increase.
D. The bacteria must adjust to the nutrient content in the new medium, synthesizing necessary amino acids, growth factors, and enzymes.

The correct answer is D. The bacteria must adjust to the nutrient content in the new medium, synthesizing necessary amino acids, growth factors, and enzymes.

Explanation:

As a bacteria enters a new medium it is not able to divide immediately because the environment of a new medium is different from the old medium. A new medium may contain a different and complex food source for which bacteria have to synthesize new enzymes and growth factors.

So initially bacteria remain in the log phase which shows that the bacteria is adjusting in its new medium and synthesizing necessary amino acids, growth factors, and enzymes required for their growth in the new medium.

Therefore the correct answer is D.