DISKORDIA · Molecular Drivers of the InteractionS between marine algicidal KORdia and DIAtoms: from coexistence to algal lysis.

Molecular Drivers of the InteractionS between marine algicidal KORdia and DIAtoms: from coexistence to algal lysis.

Marine microorganisms such as phytoplankton and bacteria play essential roles that shape the world we live in. Through photosynthesis, marine phytoplankton convert inorganic carbon into organic matter that fuels marine food webs. Marine bacteria recycle at least half of the organic matter produced by phytoplankton, which makes important nutrients and vitamins available again for phytoplankton. In addition to sustaining life in the ocean, the activity of these microorganisms impacts the concentration of carbon in the Earth’s atmosphere, which in turns affects climate. Thus, phytoplankton and bacteria need each other to thrive and perform these important functions that set the conditions for life on Earth. In the 1970s, marine microbiologists discovered unusual bacteria that behave like phytoplankton pathogens, inhibiting photosynthesis and growth, and sometimes even inducing death and cell lysis. To date, very little is known about these so-called algicidal bacteria, and important questions remain about their mechanisms of attack and the consequences of their behavior for phytoplankton physiology and activity. The DISKORDIA project was designed to shed light on several aspects of the biology of these algicidal bacteria through the study of Kordia, a genus of marine algicidal bacteria. The first discovered member of the Kordia genus, Kordia algicida, was isolated from seawater in the Masan Bay (Republic of Korea) and showed algicidal behaviour against local species of phytoplankton. Since the isolation of K. algicida, nine other Kordia isolates have been obtained from multiple oceanic regions, suggesting this bacterial group is ubiquitously distributed in the world ocean. The objective of the DISKORDIA project was to investigate the mechanisms of algicidal activity in Kordia bacteria and provide answers to the following questions: -are all Kordia species capable of algicidal activity? -what is the sensitive phytoplankton spectrum for algicidal Kordia species? -what is the effect of algicidal Kordia on sensitive phytoplankton? -what is the algicidal mechanism of Kordia species and is it the same among all of them? Answering these questions is essential to understand how they affect phytoplankton physiology and diversity and thus predict the impact of algicidal bacteria in marine systems.

Data: CORDIS, © European Union