You acquire a soil sample and run an enrichment culture on it. You provide the organisms in the culture with all of the ingredients required for growth except for nitrogen. What result do you expect to have at the end of your experiment?
A) Nitrogen-fixing bacteria will significantly outnumber those incapable of fixing nitrogen.
B) Nitrogen-fixing bacteria will not be present in the culture.
C) Nitrogen-fixing bacteria will be present but not at significantly greater numbers than non-nitrogen-fixing species.
D) Nitrogen-fixing bacteria will be present, but will be significantly outnumbered by non-nitrogen-fixing species.

Question

Quizplus · Accepted Answer

By omitting nitrogen from the culture medium, you create a selective environment that favors the growth of nitrogen-fixing bacteria, which can convert atmospheric nitrogen into a form they can use. Non-nitrogen-fixing bacteria, unable to obtain nitrogen for growth, will not proliferate under these conditions.

You Acquire a Soil Sample and Run an Enrichment Culture