The dynamic of light regulation in outdoor microalgae cultures

Microalgae are a sustainable source of biomass with applications in several fields, from food to pharmaceutical. Still, their cultivation scale-up needs some refinement to become economically competitive and improve the positive impact for the environment. By enhancing microalgae’s ability to exploit light exposure better, we can also increase biomass yield.

In fact, light is a highly variable environmental parameter: it constantly changes with the seasons, time of day and weather conditions. Microalgae have several regulatory mechanisms to handle such dynamic conditions, which, however, are not adapted to respond to artificial fluctuations typical of large-scale cultures. In addition to natural fluctuations, self-shading among individual cells is observed in large-scale cultures. This very uneven exposure to light is further unbalanced due to shuffling: cells in fact, shift and undergo abrupt changes in light exposure. While the regulation of photosynthesis has so far been studied mainly under controlled laboratory conditions, these mechanisms also have a strong impact on outdoor cultivation.

In a recent study from Tomas Morosinotto’s laboratory at the University of Padua, current knowledge on the regulation of photosynthesis and its implications for maximizing the productivity of microalgal biomass are discussed. For example, light fluctuations in the time interval between 1 and 100 seconds have a major negative impact on biomass productivity but require less rapid regulatory mechanisms to enable adequate responses.

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