Lichtgedanken 03

S C HW E R P U N K T 14 Microscopic friends and helpers In view of growing threats from global infectious diseases, multiresistant bacteria and dwindling numbers of effective drugs, microorganisms and fungi do not enjoy the best of reputations. However, these threats to our health, which must undoubtedly be taken seriously, can easily blind us to the huge significance of microbes in maintaining human health, an intact environment and a stable climate. In an interview, Jena microbiolo- gist Prof. Axel Brakhage discusses what makes microorganisms so successful and what we can learn from them. INTERVIEW: UTE SCHÖNFELDER Microorganisms are present virtual- ly everywhere: in the soil, the water and the air. How do bacteria, fungi or microalgae manage to colonize just about every habitat on Earth? A key characteristic of microorganisms is their metabolic diversity. They have at their disposal an improbably large num- ber of metabolic pathways—more than any higher organism. This makes them very flexible, so that they can adapt ra- pidly to any environmental conditions, even those that are very extreme, such as temperatures over 100 degrees Cel- sius, absolute aridity, high pressure or nuclear radiation. This enables them in principle to colonize all parts of the pla- net and, of course, all higher organisms. Plants, animals and humans provide habitats for a huge number and diversi- ty of microorganisms. Every one of us carries a kilo or so of bacteria in our in- testines, in our mouths and on our skin. Can we therefore consider diversity to be the microbial recipe for success? Without a doubt. But there is a second important factor for success, which is their abundance. There are just so many microorganisms! Their numbers exceed Prof. Axel Brakhage is Professor of Microbiology and Molecular Biology at the University of Jena and director of the Leibniz Institute for Natural Product Research and Infection Biology—Hans Knöll Institute (HKI). He coordinates the Excel- lence Initiative Graduate School »Jena School for Microbial Communication« (JSMC) and is, among other things, speaker of the Collaborative Research Centre/Transregio »FungiNet« (see box p. 11) and of the research consortium »Infect- Control 2020«.