diatom

Small ocean diatoms are very effective at absorbing carbon dioxide from the environment. In fact, they account for up to 20 percent of all CO2 absorbed.₂ on Earth, according to two papers by an international team of scientists published in Cell. Researchers have worked for a long time to learn its secrets.

Although invisible to the naked eye, diatoms are among the most prolific algae in the oceans and play a critical role in the global carbon cycle. Thanks to photosynthesis they convert it into nutrients that support most life in the ocean. Despite their huge role, how diatoms carry out this process so efficiently has remained a mystery.

Now researchers led by Professor Ben Engel from the University of Basel Biocentre, together with teams from the University of York and Kwansei-Gakuin University in Japan They discovered a protein shell critical to their ability to trap greenhouse gases so effectively. Using advanced imaging techniques such as cryo-electron tomography, they mapped the molecular structure of the PyShell protein shell and discovered its functions.

PyShell and the key to efficient photosynthesis

In plants and algae, photosynthesis occurs in chloroplasts. Inside these chloroplasts, energy from sunlight is collected by thylakoid membranes and then used by a special enzyme, Rubisco, to fix CO2.₂. But algae have an advantage: They pack all their Rubisco into tiny compartments called pyrenoids.₂ can be captured more effectively.

We found that the pyrenoids of diatoms are enclosed in a cage-like protein shell. PyShell not only gives the pyrenoid its shape, but also helps create a high concentration of carbon dioxide in this compartment. This allows Rubisco to capture CO efficiently₂ We take it from the ocean and turn it into nutrients,
– says Dr. author of both studies. Manon Demulder.

This diagram shows the arrangement of the basic elements of algae: thylakoid membranes, pyrenoids, Rubisco and PyShell / Photo: Manon Demulder, Biozentrum, University of Basel

When researchers extracted PyShell from algae, their ability to correct CO was revealed.₂ significantly worsened, photosynthesis and cell growth decreased.

This showed us how important PyShell is for efficiently capturing carbon, a critical process for ocean life and global climate.
– Adds Manon Demulder.

What does it give us in practice?

The discovery of PyShell could open promising avenues for biotechnological research aimed at combating one of the most pressing problems of our time: climate change.

First of all, we humans must reduce our carbon dioxide emissions to slow the pace of climate change. But until we do that, scientists are looking for alternatives, including capturing carbon from the air. We have already seen various technologies that propose to build facilities to collect gas and convert it into a solid for later burial or industrial use. But this natural method can work in a completely different way.

The gas we emit now will remain in the atmosphere for generations. But this discovery could lead to biotechnologies will improve photosynthesis in both diatoms and other plants. In theory, we could produce new types of genetically modified plants (trees or grasses) that could be mass-planted around the world to cleanse the atmosphere of emissions.