Surface accumulation of the nitrogen-fixing microbe Trichodesmium in the South Pacific Ocean.

Click on image for full size
Courtesy of Pia Moisander

More than One: Long-Reining Microbe Controlling Ocean Nitrogen Shares the Throne

Scientists have been taking a close look at special types of bacteria that live in the ocean. These microbes may be tiny, but they play a big part in the nitrogen cycle.

The little round bacteria are able to change nitrogen from one form to another. They take nitrogen gas from the air and change it into the type of nitrogen that other organisms need to survive. Because these bacteria can change nitrogen, they are called “nitrogen-fixing bacteria”.

These nitrogen-fixing bacteria prefer to live in certain places in the ocean. Some types live in warm water of the tropics while other types prefer cool water found in the deep sea or near the poles. Since the nitrogen-fixing bacteria only live in certain parts of the ocean, nitrogen moves through the nitrogen cycle differently in different places.

The plants and algae in the ocean that do photosynthesis need nitrogen as a nutrient. These plants and algae are the start of food chains that include almost all life in the sea, except for the life around deep-sea vents. Nitrogen-fixing bacteria transform nitrogen from the air into a form that plants and algae can use, so they are very important for marine ecosystems.

Last modified May 21, 2010 by Lisa Gardiner.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

The Domain Eubacteria

Eubacteria, also know as “true bacteria”, are microscopic prokaryotic cells. Cyanobacteria, also called blue-green algae, are Eubacteria that have been living on our planet for over 3 billion years. Blue-green...more


There is more nitrogen gas in the air than any other kind of gas. About 4/5ths of Earth's atmosphere is nitrogen gas! A molecule of nitrogen gas is made up of two nitrogen atoms. There are other molecules...more

Kingdom Plantae

Kingdom Plantae contains almost 300,000 different species of plants. It is not the largest kingdom, but it is a very important one! In the process known as "photosynthesis", plants use the energy of the...more


Photosynthesis is the name of the process by which autotrophs (self-feeders) convert water, carbon dioxide, and solar energy into sugars and oxygen. It is a complex chemical process by which plants and...more

Life in the Deep Ocean

The deep ocean is very cold, under high pressure, and always dark because sunlight can not get down that far. Less life can survive in the deep ocean than in other parts of the ocean because of these conditions. ...more

Triggers of Volcanic Eruptions in Oregon's Mount Hood Investigated

Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. "The data will help give us a better road map to what a future...more

Oldest Earth Mantle Reservoir Discovered

The Earth's mantle is a rocky, solid shell that is between the Earth's crust and the outer core, and makes up about 84 percent of the Earth's volume. The mantle is made up of many distinct portions or...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA