In 1917, Professor Nicolaas Söhngen laid the foundations for WUR’s Microbiology chair group. A century later some leading lights in the field assess his legacy. What has the world gained from one hundred years of Wageningen microbiology?
text René Didde photos Guy Ackermans, W.J. de Zwart and WUR
Autumn 1917. Groningen professor Nicolaas Söhngen arrives at the National Agricultural College in Wageningen to set up research and teaching on anaerobic microbiology. There is a shortage of space and facilities, however: he stays at Hotel de Wereld, sets up a temporary laboratory in a house, and gives his lectures in the main building on the Salverdaplein. After a year he is so fed up that he threatens to go back to Groningen. That helps. In 1920, an elegant laboratory designed by Amsterdam School architect Cornelis Blaauw goes up on the Hesselink van Suchtelenweg.
The rest is history. Not only is the Microbiology Laboratory now an immaculate listed building, but Söhngen’s big success was in laying the foundations of a rich tradition of microbiology research in Wageningen. He paved the way for research on the then newly discovered bacteriophages, highly specific viruses that attack specific bacteria. He also explored the symbiosis between Rhizobium bacteria and tubers in crops such as clover. It turned out to be a rich field of research. Remarkably, too, Söhngen saw the value from the outset of exchanging research results with players from industry and agriculture.
In the years that followed, the Wageningen chair group built up a solid reputation with its research on bacteria in their environmental context, their capacity to adapt and the way they use the results of each other’s metabolic processes. This was apparent last month at the Centennial Symposium with which the group celebrated its 100th anniversary. The study of anaerobic bacteria, for instance, led to progress in the fields of water purification and soil decontamination. But the work on gut bacteria is internationally renowned too and produced results which are used in developing new drugs. Finally, the insights into defence mechanisms against bacteriophages have generated countless new methods of genome editing, such as CRISPR-Cas. In short, there is a direct line from 1917 to 2017.
Several keynote speakers at the seminar were originally Wageningen researchers, including Mike Jetten (Radboud University Nijmegen) and Mark van Loosdrecht (Delft University of Technology), both Spinoza Prize winners. Their lectures gave an overview of Wageningen research. ‘What kinds of micro-organisms are there, what do they do, how do they communicate, do they collaborate, and how can you use them for social or industrial purposes – whether alone as pure cultures or together as mixed cultures which can do the trick faster?’ That is the summary of Wageningen microbiology offered by another Spinoza Prize winner, Willem de Vos, Wageningen professor for 30 years and Söhngen’s fourth successor for the last 25. ‘The integration of microbial physiology, ecology and genetics is characteristic of our research, and gut microbiota and bacterial defence systems are still fruitful areas of research along with water purification and soil decontamination,’ he says.
An example is Mike Jetten, who was involved in environmental microbiological research on topics including water purification and the role of the Anammox bacterium. This micro-organism converts ammonia and nitrite from wastewater into nitrogen gas under anaerobic conditions. This research too is directly descended from the very first research on anaerobic bacteria and the nitrogen cycle, which started a century ago.
Another ‘anaerobic’ example is the Akkermansia bacterium. ‘We isolated it in the human gut, and analysed it genetically and in the ecology of the gut microbiotica,’ says De Vos. ‘Then we used the bacterium in animal tests, and an improvement in the barrier function of the gut was demonstrated in mice. Now we are working on developing this anaerobic bacterium as a treatment for people with diseases of affluence such as obesity and type 2 diabetes.’
Jan Roelof van der Meer, professor at the University of Lausanne, was on the list of keynote speakers too, but he broke his shoulder and could not attend. ‘I got addicted to microbiology through my research on soil as a Wageningen student and PhD candidate,’ he explains on the phone. ‘ It is an excellent trend that we no longer only work with pure cultures, but focus on mixtures of bacteria instead. Because that is the reality now. You can see it happening everywhere, and certainly in Wageningen,’ says Van der Meer.
Mark van Loosdrecht (Delft University of Technology) is especially full of praise for the interdisciplinary research culture. ‘That is the basis for successful research, and can deliver the breakthroughs we need in the fields of agriculture, nutrition and the environment. In the 1980s and 1990s, this laid the foundations for successful soil decontamination.’ Among other things, he is referring to bacteria which, after some adaptations, were effectively able to break down organic solvents in the soil. Compared with the then standard thermal and chemical methods of soil decontamination, the new biological method vastly reduced the requirements for energy, excavation and transport.
One of the things Van Loosdrecht himself made his name for was the Nereda process, in which bacteria form clumps of granulated sludge and sink fast, saving time, energy and space in water purification. The granules grow by making smart use of both oxygen-rich and oxygen-poor conditions. The basis for this is ‘biofilms’, which Van Loosdrecht did research on when he was in Wageningen.
But like Van der Meer, Van Loosdrecht is not inclined to talk of some sort of ‘Wageningen School’. ‘There is more of a Delft School,’ he says, in a nod to his current employer. ‘Söhngen was a student of Beijerink’s, and he was at Delft. Söhngen discovered that methane is formed in places like swamps by bacteria, and he successfully expanded that research in Wageningen. So I would describe Wageningen as the anaerobic branch of the Delft School.’
But there are people who left Delft for Wageningen, such as the famous Gatze Lettinga. Back in the 1970s, Lettinga developed a compact reactor for use for anaerobic water purification in industry and in the Third World. Wastewater purification with this reactor required no energy, instead actually producing energy in the form of biogas, says Willem de Vos. And he knows of another example. ‘The Delft-based Beijerink taught at the Agricultural College too, where he discovered plant viruses and did research on the nitrogen cycle.’ In short, all these professors of microbiology are not unlike a cocktail of different bacteria. They turn up all over the place, they communicate with each other and pass on the results of their work to each other. And they collaborate in the – there he is again – Söhngen Institute for Anaerobic Microbiology.