A group of bacteria lives in close association with other organisms throughout the world's oceans. Microbiologist Meinhard Simon and his team at the recently completed Collaborative Research Centre Roseobacter have spent 13 years investigating what makes these microbes so successful.

The sea is full of life. Even a thimbleful of water from the vastness of the ocean contains up to a million tiny creatures: Bacteria.

It is the size of these microscopic organisms that fascinates Prof. Dr Meinhard Simon: "Bacteria are the most abundant and diverse organisms." For the microbiologist, the interactions that microorganisms have with each other, with other living organisms and with their environment form "a world of its own". A finely woven world about which researchers now know much more than they did years ago, thanks in part to his work.

Simon, who was a professor at the university's Institute of Chemistry and Biology of the Marine Environment from 1997 to 2023, has been studying a particular part of the bacterial world for many years: the Roseobacter. These microbes play an important role in the global cycle of elements such as carbon, nitrogen and sulphur, for marine food webs and ultimately for our climate. From 2010 to 2022, the microbiologist is the spokesperson of a collaborative research centre funded by the German Research Foundation (DFG), in which more than 60 researchers from Oldenburg, Braunschweig, Göttingen and Bonn are working on these organisms, which are only a few thousandths of a millimetre in size.

A largely unknown group of bacteria

Simon and other researchers, such as Prof. Dr Irene Wagner-Döbler from the Technical University of Braunschweig and his Oldenburg colleague Prof. Dr Thorsten Brinkhoff, discovered the first representatives of Roseobacter by chance in the late 1990s and early 2000s in samples from very different regions of the world's oceans - from the North Sea to the Southern Ocean.

Until then, this group of bacteria had been largely unknown. This sparked the curiosity of the researchers: What makes the bacteria and their metabolism so special that they can adapt to such different environmental conditions? And how do Roseobacter fit into the web of life in the sea?

The researchers were able to carry out initial studies and even decode the genetic material of some species - a complex and expensive undertaking at the time. This preliminary work ultimately enabled the interdisciplinary team to obtain DFG funding for the Collaborative Research Centre in 2010.