How do plants and animals get nitrogen if not from the atmosphere?

All plants and animals need nitrogen to make amino acids, proteins, and DNA, but the nitrogen in the atmosphere is not a form that they can use. When organisms die, their bodies decompose bringing the nitrogen into soil on land or into ocean water. Bacteria alter the nitrogen into a form that plants are able to use.

Bacteria alter the nitrogen from decomposing bodies of other organisms into a form that plants are able to use.