A new spectrometer to measure photosynthesis in highly diluted microalgal samples
Martina Di Gisi
Photosynthesis is one of the most fundamental biological processes, sustaining life on Earth by converting light energy into chemical energy. It is carried out by a wide variety of organisms, forming the foundation of ecosystems by driving oxygen production and regulating global carbon and energy cycles. While photosynthesis in terrestrial plants has been extensively studied, its aquatic counterpart remains relatively underexplored. This gap limits our understanding of a significant portion of photosynthetic biodiversity. The main challenge lies in the lack of sensitive tools to measure photosynthesis in diluted samples. This limitation is particularly relevant for microalgae, a diverse group of photosynthetic species with extensive applications in biotechnology and environmental conservation strategies.
The European Research Council (ERC) funded PALMADS project aims to address this challenge by developing a high-sensitivity absorption difference spectrometer to measure photosynthesis in diluted microalgal samples, enabling the exploration of the aquatic photosynthesis biodiversity. The PALMADS project, coordinated by the french Centre National de la Recherche Scientifique (CNRS), will run from May 1, 2024, to October 31, 2025, with an EU contribution of €150,000.
Unveiling the hidden diversity of microalgae
Microalgae are emerging as one of the most promising biological resources of the 21st century. As primary producers in aquatic ecosystems, they sustain carbon fixation, oxygen production, and nutrient cycling. Remarkably, they are responsible for nearly 50% of the Earth’s total primary production. These characteristics have made them an attractive asset for various applications, such as biofuels, where microalgal lipids serve as precursors for biodiesel and other renewable energy sources; nutraceuticals and pharmaceuticals, due to their ability to produce omega-3 fatty acids, antioxidants, and other bioactive compounds; and environmental monitoring, as microalgae act as bioindicators of water quality and ecosystem health.
Photosynthesis is the engine that drives microalgal growth, metabolism, and productivity. The efficiency of this process determines the amount of biomass produced, the carbon captured, and the viability of microalgae as an industrial resource.. Variations in photosynthetic efficiency also provide insight into how microalgae respond to environmental changes, reflecting the overall health of the aquatic environment.
Despite its importance, measuring photosynthesis with precision remains a major challenge. Current techniques, such as chlorophyll fluorescence and oxygen evolution assays, are primarily designed for laboratory cultures, where cells grow under controlled, high-density conditions. These methods fail to capture the complexity of photosynthesis in natural environments, where microalgal populations exist in much lower concentrations and are influenced by fluctuating external factors.
Furthermore, only a small fraction of microalgal species can be cultivated, and even fewer reach high cell densities. As a result, much of their photosynthetic diversity remains unexplored, limiting opportunities to study species with significant industrial potential.
How the PALMADS Project can transform photosynthesis measurement
The ERC-funded PALMADS project is developing a high-sensitivity absorption difference spectrometer to measure photosynthesis in highly diluted microalgal samples. Unlike conventional spectrometers, which struggle to analyze low-density natural samples, this technology will provide precise and reliable measurements under natural conditions.
This breakthrough will significantly expand our understanding of photosynthetic diversity in aquatic ecosystems, improving environmental monitoring and uncovering new response mechanisms to environmental cues. It can provide new insights into how different microalgal species regulate photosynthesis under varying conditions such as light availability, nutrient fluctuations, and temperature shifts. Many microalgae have evolved distinct adaptations, including alternative metabolic pathways and regulatory mechanisms that enhance photosynthetic efficiency.
Understanding these processes will open up new possibilities for biotechnology, helping identify microalgal strains with superior photosynthetic efficiency for large-scale biofuel production, high-value compound synthesis, and other industrial applications. Exploring the diversity of photosynthetic mechanisms could also reveal alternative metabolic pathways that can be exploited for more efficient and sustainable bioprocesses.
Furthermore, photosynthetic adaptations in extreme environments can help improve crop performance. Certain microalgae optimize light capture and resource use under harsh conditions, such as those triggered by climate change, including high temperatures, drought, and soil degradation. We could apply this knowledge to enhance crop resilience, making them more adaptable to changing climatic conditions and helping to safeguard global food production.
Scientific advancements often rely on technological innovations that push the boundaries of what can be measured and understood. The PALMADS project is a clear example, as it aims to overcome a main limitation in photosynthesis research, enabling a deeper exploration of photosynthetic diversity in aquatic ecosystems.
This discussion highlights photosynthesis as both a fundamental biological process and a key factor in addressing pressing global challenges. Exploring its biodiversity provides valuable insights that drive advancements in environmental monitoring and different industries. These discoveries have significant implications for food security and renewable energy, shaping new strategies for a more sustainable future.
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