Unknown bacteria – an important part of biodiversity

Bacteria have a major impact on our environment, partly because they are big contributors to the oxygen in the atmosphere. They also top the scale in having the greatest biodiversity of all the Earth’s organisms.

“Single-celled organisms make up the absolute majority of biodiversity on our planet,” says Eva Lindström, professor at the Department of Ecology and Genetics, Limnology, and shows an illustration of what is called ‘the universal tree of life’, where you can see that animals, plants and fungi form just a small twig.

“It was only after we could start using genetic methods in the 1990s that we were able to understand this. But it’s not really that strange, considering that for billions of years single-celled organisms were all that existed on our planet,” she says.

Bacteria are important for biodiversity

Today 90 per cent of bacteria are still unknown. Eva Lindström’s research focuses on patterns in the biodiversity of bacteria and their importance in ecosystems.

“One research project is investigating why biodiversity is higher in the soil than in water. Most soil bacteria cannot survive in water due to predators or something else in the environment,” she says.

In another research project, a doctoral student is studying how bacteria get energy. For a long time, it was thought that, like humans and animals, bacteria get energy only from organic compounds. Now, however, scientists have seen that 80 per cent of marine bacteria have genes that allow them to utilise light to get energy, like plants.

“It’s really cool that they survive in a way we hadn’t considered previously,” says Eva Lindström. With the study, she aims to find out if this type of bacteria is also found in lakes and on land.

“We want to see what effects this has on ecosystems. Theoretically, it could affect how much carbon dioxide the bacteria produce.”

An unexpected way to get energy

Humans and animals have rhodopsins in their eyes to absorb light and thus be able to see. Some bacteria use rhodopsins instead to get energy.

“This is quite different from photosynthesis in plants. The bacteria don’t have the ability to absorb carbon dioxide,” says Eva Lindström, who also says that theoretically, they could still affect the carbon balance.

“When bacteria break down organic compounds, carbon dioxide is produced. If they can also use light, they need less energy from organic compounds.”

Her research belongs to the Area of Advance Evolution and biodiversity in a changing world. One aspect that Eva Lindström would like to highlight about bacteria is their link to climate change.

“It’s important to know how natural ecosystems affect the climate. When it comes to bacteria, we may need to rethink how ecosystems function,” she says.

Sigrid Asker