VU microbiologist and microbial ecologist Matti Gralka sets out to understand how bacteria change algae growth in Dutch coastal waters. With his research project "Microbial friends and foes in a warming ocean" he wins an NWO Vidi grant.
How well algae grow impacts marine ecosystems and depends on not only on water temperature, but also the surrounding bacterial species. However, there are so many possible combinations of algae and bacteria that at the moment, their combined effects are impossible to model. VU microbiologist and microbial ecologist Matti Gralka and his team develop a way to make better predictions.
Gralka: "Marine phytoplankton are microscopic algae that carry out about half of all photosynthesis on Earth. Each algal cell releases sugars, amino acids and other compounds into a thin layer of water around it, called the phycosphere. Dozens to hundreds of bacterial species live in this layer. Some help the alga, for example by supplying vitamins. Others compete with it for nutrients or kill it directly. Together, these interactions affect how much carbon the ocean takes up."
"The same bacterium can help an alga at one temperature and harm it at another. Studies of how warming changes these interactions give contradictory results. Most knowledge comes from a few well-studied species pairs, and there are far too many combinations of species and temperatures to test one by one. As a result, models of the future ocean carbon cycle do not describe the effect of all these bacteria on algae at all."
From Traits to Predictions
In this Vidi project, microbiologist and microbial ecologist Matti Gralka and his team will test whether the outcome of an interaction can be predicted from properties measured on each partner separately, such as their growth rate and the compounds each partner releases or consumes.
They will study the interaction of hundreds of pairs of algae and bacteria from Dutch coastal waters using new high-throughput methods they will develop. In the end, they combine the experimental data in a mathematical model that can predict how these interactions change with temperature.
Wider Impact
"Our results can help ocean scientists make better models with a more accurate description of how algae grow under different conditions, which helps make better predictions of marine ecosystems in future climates. They can also help companies that grow algae to design more stable cultures. Our long-term goal is that this approach can be used for other microbial communities, such as those in the gut or in soil, to be able to make better predictions in microbial ecology."