Marine microbiology
Viruses and bacteria

Viruses and bacteria

Viruses and bacteria - groups with central roles in the marine ecosystem.

Viruses (small green dots) and bacteria (larger green dots) from a sea water...
Viruses (small green dots) and bacteria (larger green dots) from a sea water sample. The sample is stained with SYBR Green, a fluorescent stain that binds to DNA. More DNA means more of the reagent attached. Bacteria hold more DNA compared to viruses and will therefore glow more intensively.


Viruses exist everywhere life is found, and also in the sea. An estimate of their abundance is 107 viruses per mL sea water. Viruses have the capacity to infect everything from bacteria to blue whales and play therefore crucial roles in the processes going on. For example, they may be important in termination of algal blooms, and they are important in nutrient cycling. In the research group we have several ongoing projects related to viruses infecting algae.

 Also bacteria are found everywhere in the ocean and in great quantity – roughly 105 to 107 cells per mL. And there is a great amount of diversity, and estimate is 1,000 to 10,000 types per mL seawater. However, only a tiny fraction seems to be active at a given moment. And different strains of bacteria thrive under different conditions.

In our research group we investigate how bacteria are distributed over depth, region, and time. We assess the role of the microbes in their natural habitat, for example are pelagic bacteria not only feeding on dead organic matter, numerous groups have light-based energy acquisition mechanisms. And we are especially interested in questions regarding how bacteria function to structure the food web.