Optimization of Culture Conditions for Arthrospira platensis Cultivation in Closed Tubular Photobioreactors

Abstract

Background: Tubular photobioreactors (PBRs) enhance high-quality Arthrospira platensis biomass production. However, microalgae are highly susceptible to micro-environmental fluctuations, specifically the combined influence of photo-thermal stress, dissolved oxygen (DO) accumulation, and hydrodynamic shear stress.  Aims: To evaluate A. platensis growth dynamics and biochemical composition under environmental stressors to establish safe, sustainable operating limits.  Study Design: Experimental study utilizing a one-factor-at-a-time (OFAT) screening approach.  Place and Duration of Study: Institute of Life Sciences, Vietnam Academy of Science and Technology, Ho Chi Minh City, Vietnam, between March and July 2025.  Methodology: The experiments investigated illumination modes, circulation velocities (0.1-0.5 m/s), and aeration cycles (9 h/day and 24 h/day).  Results: We have established an optimal safe operation window using shading roof (28-32 °C), 0.3 m/s circulation velocity and continuous aeration (24 h/day). The maximum biomass production was 3.49 g/L after 7 days, corresponding to 0.456 g/L/day, with enhanced phycocyanin (123.37 mg/g), carotenoid (4.02 mg/g), and crude protein (59.20%) contents. Conclusion: These findings provide practical guidance for alleviating environmental stress and improving large-scale cultivation of A. platensis under tropical conditions.