Azotobacter species are unusual in that they have extremely high respiratory rates and are among the few obligate aerobes able to fix molecular nitrogen. It is believed that the high respiratory rates result from the extensive membranous network that this genus of organisms possess and that a purpose of these high respiratory rates may be to protect the oxygen-sensitive nitrogenase enzyme complex by scavenging molecular oxygen. Therefore, any relationship that exists between respiration rate capability, intracellular membrane formation, and nitrogen fixation are of special interest. [...]