Nitrogen fixation occurs in nature either due to lightning or nitrogen-fixing bacteria. Importance: Nitrogen-fixing bacteria are very important because they provide the plant with nitrogen and fertilize it. Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids, the building blocks of proteins.