Photosynthetic Activity in Low Micro-Algal Density Suspensions

Photosynthesis is at the intersection of many vexing problems facing humanity, including feeding an ever-increasing population, securing the agricultural economy, replacing fossil fuels with renewable energy, and responding to climate changes. Studying this fundamental process and exploring its functional biodiversity is a crucial necessity.

Indeed, photosynthesis is a perfect tool for environmental monitoring in a context of climate changes; it probes in a non-invasive way the physiological state of a photosynthetic organism, its response to the environment.

Moreover, the discovery across diversity of new response mechanisms to environmental cues, new metabolic pathways or regulatory mechanisms also constitutes a reservoir for biotechnological mining or crop improvement.

In-depth measurements of plant photosynthesis are now possible in the field with the development of dedicated portable instruments, combining chlorophyll fluorescence and absorption difference spectrometry.

However, such approaches do not exist in the aquatic world, where most of the diversity of photosynthetic organisms is yet located, because the sensitivity of absorption difference spectrometers is not sufficient for natural samples characterized by very low concentrations of microalgae.

Furthermore, a very small proportion of microalgal species are currently cultivated and of these, very few are lab rats reaching high cell concentrations. For all these reasons, a huge part of photosynthetic biodiversity escapes us.

In this project, we propose to develop a high sensitivity absorption difference spectrometer which will allow measuring photosynthesis in diluted samples of one or more microalgal species.

We believe that the development of such an instrument will constitute a real breakthrough in the study of photosynthesis, allowing to explore the diversity of architectures, pathways and regulations of aquatic photosynthesis.