Final answer:
Denitrifying bacteria would remove nitrates from contaminated water by converting it into nitrogen gas.
Step-by-step explanation:
In the nitrogen cycle, nitrifying bacteria play a crucial role in converting ammonia to nitrite and nitrite to nitrate.
However, to remove nitrates from contaminated water, denitrifying bacteria are needed.
Denitrifying bacteria convert nitrates into nitrogen gas, which can then be released back into the atmosphere.