In oxygen-rich environments, cyanobacteria have evolved elegant strategies to protect nitrogenase an enzyme highly sensitive to oxygen while still performing photosynthesis. One key mechanism is temporal separation, where photosynthetic oxygen production occurs during the day, and nitrogen fixation takes place at night. During this dark phase, enhanced respiration rapidly consumes intracellular oxygen, creating microoxic conditions that allow nitrogenase to function safely. Energy metabolism is tightly linked to this process, as stored carbon compounds generated during photosynthesis fuel respiration and nitrogen fixation in the absence of light. Additionally, temperature plays an important regulatory role, influencing both nitrogenase efficiency and the balance between respiration and photosynthesis, ensuring optimal enzyme activity under varying environmental conditions.