Azospirillum is a member of the bacterial species that fix nitrogen. Additionally, the procedure uses energy. However, this bacteria can function to some extent in both aerobic and anaerobic environments. Only when oxygen is not present does nitrogen-fixing take place. The soil and plant parts have oxygen. However, these bacteria require anaerobic conditions. So, the bacteria have leghaemoglobin molecules. Leghaemoglobin, which binds to oxygen molecules to maintain the oxygen in plant roots, creates an environment that is appropriate and oxygen-free for bacterial operation.