Lichtgedanken 03

S C HW E R P U N K T 43 03 | LICHT GEDANKEN Contact Prof. Dr Erika Kothe Institute of Microbiology Neugasse 25, D-07743 Jena, Germany Phone: +49 36 41 9-49 291 Email: erika.kothe@uni-jena.de www.mikrobiologie.uni-jena.de Original Publications Stone-Eating Fungi [...]. Advances in Applied Microbiology (2017), DOI: 10.1016/ bs.aambs.2017.01.002; Calcium carbonates: Induced biomineralization with controlled macromorphology. Biogeosciences (2017), DOI: 10.5194/bg-2017-251 penetrated the rock and formed etch pits under the growing fungal hyphae to a depth of approximately 200 nano- metres,« explains Kothe. »Black slate is rich in organic material, which is used by the fungus for nutrition.« To establish which factor is ultimately decisive for this behaviour, the re- searchers switched off individual genes of the fungus. After knocking out the gene responsible for the forma- tion of laccase, they obtained confirma- tion of their hypothesis. Furthermore, they discovered that Schizophyllum commune produces a par- ticularly large amount of the enzyme when grown with the rock material present—probably because it needs more of this enzyme in order to gain access to its food source. These findings might help to develop new methods for reclaiming land that has been mined. By breaking down the organic material in the rock, the fun- gus dissolves the heavy metals embed- ded in it. These metals are thus con- centrated in the water. With the help of the fungus, such heavy metal residues could therefore be removed biologi- cally. »This shows us yet again the po- tential of microorganisms,« says Erika Kothe, »and we will continue with our research on these interactions between biosphere and geosphere in the future, together with our colleagues from Geosciences.« The mineral calcite consists of calcium car- bonate. It is usually a colourless mineral, which dissolves with carbon dioxide emis- sion in an acidic environment. Characteristic for calcite crystals is their birefringence: incident light is split into two rays of light with different refractive indices. Calcite is a rock-forming mineral and it occurs, for ex- ample, in marble and limestone. Stalactites and stalagmites in caves may also consist of calcite. Calcite crystal on mineral realgar from China (mineralogical collection of the University Jena). Vaterite , which is chemically related to calci- te, also consists of calcium carbonate, but differs from calcite in its crystalline structure. As a result, the significantly rarer vaterite has different characteristics: it forms only small, filamentous crystals and is harder to dissol- ve than calcite. Vaterite forms in mineral-rich springs and also in organic tissue. It is a con- stituent part of gallstones and kidney stones, for example. The rock called travertine consists mainly of cal- cite (calcium carbonate), which precipitates as »fresh-water limestone« from warm or cold springs. Well-known features are, for example, the »travertine terraces« in Pamukkale, Turkey, or in Mammoth Hot Springs, Yellowstone National Park, USA. The rock is light in colour, usually yellowish and brown, and has a porous structure. Travertine is used as build- ing material, for example in many historical struc- tures such as churches. The fungus Schizophyllum commune (split gill fun- gus) is widespread and found all over the world. Especially interesting is the fact that this fungus forms more than 20,000 different »sexes« or mating types, enhancing the probability of reproducing sex- ually with outbreeding, and limiting inbreeding ge- netically. It occurs as a typical cause of white rot on deciduous and coniferous trees. Schizophyllum commune produces fruiting bodies on dead wood, but also in petri dishes. Along with other fungi, it appears in the special exhibition, »Dem Ge- ruch auf der Spur—Die chemische Sprache der Natur« (Following the scent—nature’s chemical language), in the Phyletic Museum of the University Jena until autumn 2018. B A C K G R O U N D F E AT U R E