nitrifying bacterium

plural nitrifying bacteria

Definition of nitrifying bacterium

: any of various aerobic gram-negative bacteria (as of the genera Nitrosomonas, Nitrosococcus, and Nitrobacter) commonly found in soil and water and obtaining energy through the process of nitrification They are nitrifying bacteria, formerly believed to occur only in the soil and natural water systems, where they play key roles “fixing” nitrogen and making this element available to growing plants. — Bernard Dixon, The Independent (London), 16 Nov. 1992

Note: Nitrifying bacteria are sometimes classified in the paraphyletic family (Nitrobacteraceae).

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

First Known Use of nitrifying bacterium

1880, in the meaning defined above

Keep scrolling for more

Learn More about nitrifying bacterium

Statistics for nitrifying bacterium

Look-up Popularity

Time Traveler for nitrifying bacterium

The first known use of nitrifying bacterium was in 1880

See more words from the same year

Comments on nitrifying bacterium

What made you want to look up nitrifying bacterium? Please tell us where you read or heard it (including the quote, if possible).


miscellaneous remnants or debris

Get Word of the Day daily email!

Test Your Vocabulary

The Exceptions Quiz III

  • one green toy robot amidst many red toy robots
  • Which of these words does not mean "nonsense"?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!