Phytoplanktons are the foundation of life in the ocean and powerful natural carbon sinks. Phytoplankton feeds everything – from tiny animal-like zooplankton to multi-ton whales. Diatoms are a single-cell algae with the size of half a millimeter that live in the surface water of the world’s oceans.
They are special in that they are one of the world’s biggest resources for removing CO2 from the atmosphere. They soak up and sequester 10-20 billion metric tons of CO2 every year via the process of photosynthesis. The science community is now looking into what biological mechanisms diatoms are using to concentrate CO2 and whether the levels of their CO2 sequestration will change with rising ocean acidity, temperatures and CO2 levels in the atmosphere.
New Diatoms Study
A new study in Frontiers in Plant Science sheds some light into those questions. The study claims that marine diatoms mainly use one pathway to concentrate CO2 at the vicinity of carbon fixing enzyme. The good news is the process diatoms have, continues unchanged even at higher CO2 levels. It has no effect on gene expression and the abundance of the five key enzymes used in carbon fixation.
In nature, plants have various mechanisms for concentrating CO2 from the air, or water, and transforming it into organic substances. The carbon-fixing enzyme, RuBisCO, is not very efficient in storing CO2, so plants keep high levels of CO2 at the vicinity of the enzyme.
The researchers that participated in the study are also interested to examine how often the genes of five key carbon-fixing enzymes are present, and whether their abundance and expression levels depend on location and conditions.
According to another research, an enzyme called carbonic anhydrase is ten times more abundant than others in diatoms. That fact proves that instead of biochemically transforming CO2 first, diatoms are actively pumping in dissolved CO2 inside the cell.
The study has indicated that despite the varying levels of carbon dioxide in the environment, the diatoms are highly efficient in concentrating it inside the cell. The team has also highlighted the different patterns of key enzymes’ gene expression varied depending on latitude and temperature. However, the researchers are waiting on new datasets from expeditions to learn more.