Effect of Low Atmospheric Pressure on the Growth and Antioxidant Defense Response of Dunaliella Salina

Space explorations on Mars are compelling scientific endeavors that provide critical information on how to establish life on the planet. Designing a bioregenerative life support system capable of supplying food and oxygen is essential for long-duration human missions to Mars. The atmospheric pressure on the Martian surface is significantly lower than that on Earth, and the ability of photosynthesizing organisms to grow under such low atmospheric pressures is crucial for developing a life support system. Dunaliella salina, a unicellular microalga, is a rich source of the valuable metabolite β-carotene. This alga exhibits rapid growth, tolerance to environmental stress, and potential as a candidate for space studies. This study investigated the effect of low atmospheric pressure (860, 340, 160, and 80 mbar) on growth, chlorophyll pigments, and antioxidant enzyme responses in D. salina. The results demonstrated that growth, cell number, density, and chlorophyll content increased under 340 and 160 mbar pressures but significantly decreased at 80 mbar. Protein content increased by 32.1% at 340 mbar, declining at 80 mbar. Reduced growth under 80 mbar atmospheric pressure resulted in the high accumulation of carotenoid content (13.4 mg g⁻¹) and β-carotene (9.4 mg g⁻¹). Superoxide dismutase increased with decreasing atmospheric pressure, while catalase activity declined at 80 mbar. These findings suggest that the ability of D. salina to grow under varying atmospheric pressures is linked to alterations in cellular metabolism and enhanced antioxidant capacity.