Also found in: Medical.
Related to denitrifying bacterium: Nitrifying Bacterium
Any of various bacteria that convert nitrate or nitrite into nitrogen gas in the absence of oxygen and play an important role in the nitrogen cycle.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.