Abstract

Photosynthesis is a fundamental process in microalgae, playing a crucial role in global carbon cycling and biotechnological applications. However, methods for measuring photosynthesis in microalgae remain underdeveloped compared to terrestrial plants. This study explores the application of Infrared Gas Analyzer (IRGA) technology to assess photosynthetic performance in Isochrysis galbana, a commercially valuable marine golden-brown microalga. IRGA enables real-time CO? exchange measurements in an open system, providing insights into carbon fixation dynamics when combined with chlorophyll a fluorescence analysis. The photosynthesis–irradiance and CO?–response curves of I. galbana were characterized, revealing saturation at high-light intensities and CO? levels, indicating potential limitations in carbon fixation. This study established new thresholds for optimal light and CO? conditions in I. galbana cultivation, with significant implications for aquaculture and large-scale production. Additionally, the effectiveness of IRGA in microalgal biotechnology is discussed, considering its potential advantages and limitations in large-scale applications. These findings contribute to the optimization of micro-algal biotechnology, particularly in outdoor environments where light and CO? availability fluctuate. Future research should focus on integrating IRGA data with metabolic and genetic approaches to enhance photosynthetic efficiency and sustainable biomass production. © The Author(s), under exclusive licence to the European Photochemistry Association, European Society for Photobiology 2025.