Bo Barker Jørgensen has been awarded the Jim Tiedje Award 2010 for his outstanding and lifelong research efforts in the field of microbial ecology

Professor Bo Barker Jørgensen, Centre for Geomicrobiology, has received the Jim Tiedje Award 2010. The prize is awarded every second year at the International Symposium on Microbial Ecology, and goes to a researcher whose contribution to the field of microbial ecology is outstanding and lifelong.

2010.08.26 | Christina Troelsen

The award was presented at the International Society for Microbial Ecology (ISME) Conference in Seattle, USA, on Tuesday 24 August.

A long track record

The sea and the sea bed are Professor Jørgensen’s element. For more than thirty years, he has conducted research into the ecology of marine microorganisms, and he has extended and challenged our basic understanding of the matter cycle in the oceans. This award recognises both the long haul and the breakthroughs in his research.

The sulphur pearl of Namibia

Exploring the life of the giant sulphur bacteria is an important line in Professor Jørgensen’s research. It traces right back to his PhD dissertation in 1977 and onwards to his latest article published in July this year. An old stamp from Namibia and the front page of the journal Science are also witness to the fact that his results have attracted attention in distant parts of the world. In 1999, when Professor Jørgensen and his research group discovered the giant sulphur bacteria – named Thiomargarita – in sediments off the coast of Namibia, Science decided to clear its front page to make way for a picture of the bacteria. An unusual form of communicating research results also took place at the same time, when Namibia depicted the “sulphur pearl” on its official stamps.

Important for processes in the sea bed

Thiomargarita are conspicuous in a number of ways. Because of their size and the luminous white beads of sulphur, which are what they live on, the bacteria are visible to the naked eye. They have another important property, which is making sure that hydrogen sulphide – the powerful cellular poison – is not released into the water column. Along with other genuses of large sulphur bacteria, they are widespread in the sea bed and they play an important role for the different cycles down there. As Professor Jørgensen already made clear in his PhD dissertation, the enormous filamentous sulphur bacteria not only exist as “mats” we can register on the surface of the sea bed in connection with oxygen depletion, but they also normally remain concealed in the sea bed.

Extreme commuters

But how do the sulphur bacteria manage to survive at all in the sea bed? Niels Peter Revsbech’s development of micro-oxygen electrodes thirty years ago made it possible to demonstrate that the giant bacteria live in the border area between oxygen and sulphide, and that they are highly specialised in utilising this ecological niche. The discovery of the sulphur bacteria’s special adaptation that enables them to convert hydrogen sulphide in the sea bed led Professor Jørgensen and his research group to Chile, where the concentration of sulphur bacteria is particularly high. In Chile, the group discovered that the closely related bacteria colonising extensive areas of the sea bed there pump nitrate from the sea water into a water bag (vacuole) inside the cell and use it to breathe with. These strange multicellular bacteria can be up to 5–7 centimetres long and they commute up and down between the surface of the sea bed and the underlying sulphide-rich sediment, where they get their energy. While searching for similar bacteria off the coast of Namibia, the researchers found the spherical Thiomargarita instead. These bacteria can exist in the mud for months on end without supplies of nitrate to breathe, and they are the largest bacteria in the world – measured in terms of both physical size and media coverage.

More information

Professor Bo Barker Jørgensen
Centre for Geomicrobiology
+45 8942 3314
bo.barker@biology.au.dk

April 1999: front page coverage in Science showing the giant bacteria Thiomargarita, which Professor Jørgensen's research group discovered off the coast of Namibia. Research into these large sulphur bacteria is one of the long lines in Professor Jørgensen’s career as a researcher.

By Camilla Nissen Toftdal, Centre for Geomicrobiology