Wetenschap - 20 juni 2011

Our microscopic allies

Bacteria are our best friends, says personal professor Hauke Smidt. On Thursday 16 June, the 43-year-old professor of Microbiology gave his inaugural lecture on our relationship with these invisible ‘beasties’. Which goes a lot further than hosting them in our bowels.

Antoon_Akkermans.jpg
Antoon_Akkermans.jpg

Foto: .

Bacteria
Whether we like it or not, bacteria are an indispensible element in our existence. They live both on and in the bodies of humans and animals. Vast numbers of them inhabit our intestines, skin and any other parts of our bodies, moist and less moist. According to Smidt, people carry roughly ten times as many cells of micro-organisms as they do cells of their own bodies. A total of about one kilo. Quite a job to research and understand such a diverse community, but that is exactly what Smidt does. He is an ecologist specializing in the invisible world of microbiota: a micro-ecologist.  'There are more than 1,000 species of microbiota living in people and animals, between 100 and 200 species per individual', explains the micro-ecologist. 'That is quite a zoo to map out.'

Biomarker
Over years of microbial exploration, the importance of these tiny beings has been established beyond dispute. For example, the residents of our intestines are indispensible for the digestion of nutrients such as vitamins, fatty acids and amino acids. They also stimulate the immune system. One focus of Smidt's research is the identification of the various species by means of DNA analysis. Thanks to this sort of molecular biology technique, research has made great strides over the past ten years. 'If you can map out the micro-organism composition for 1,000 people or animals, you start seeing trends. For example, that certain diseases go together with a certain composition', explains Smidt. 'Like that, you may be able to identify an unhealthy situation at an early stage, so that the microbiota function as biomarkers.'

Chemical weapons
The professor does not look only at the bacteria in the intestines, but is also interested in the bacteria species found in marine sponges. Just as they do in mammals, micro-organisms live in harmony with sponges, to their mutual benefit. A sponge appears to be a very popular host: at least half of the sponge's weight can consist of bacteria. In exchange for accommodation, the bacteria help the sponge with manufacturing all sorts of chemicals which the animal can use as chemical weapons in self-defence. These substances could be useful for humans, in combatting diseases such as cancer for example. Smidt is especially interested in the synthesis route used by these substances. He once again uses molecular biology methods to figure this out and bring to light all the genetic information about the bacteria in the sponge.

Gut microbiota are not only highly promising for combatting diseases, but they can also help us get rid of stubborn environmental pollution. There are several species that are capable of breaking down chemical substances step by step. Smidt focuses in this area of the role of different species of bacteria in the systematic conversion of, for example, chlorinated hydrocarbons. And so our relationship with these little 'beasties' gains a new dimension: something like the parent-child relationship when Dad or Mum clean up after the kids. 'Microbiota are much more than a threat. In fact, our existence is unthinkable without these fascinating organisms', concludes the professor.

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