Lichtgedanken 03

S C HW E R P U N K T 13 03 | LICHT GEDANKEN Soil and rock as habitat There is a wide diversity of microbi- al life not only in habitats on the sur- face, but also—and especially—under- ground. Researchers assume that one third to one half of all the biomass on our planet is produced below ground – by microorganisms. Whether in woods, fields or in your gar- den at home: the soil is teeming with a wide variety of life forms. Soil bacteria and fungi live mainly among the roots of plants in the soil. There, they help make organic material decompose, pro- vide nutrients and break down harmful substances. However, microorganisms are also at home in layers of rock deep underg- round. Some bacteria and archaea are capable of living at depths of several ki- lometres, at extreme temperatures and under high pressure. They need neither organic material nor light in order to survive, but use inorganic rock to gene- rate energy. These organisms have very slow metabolism and it is estimated that some divide only once every 1,000 years. In current research projects, micro- biologists of the University of Jena are studying, for example, how fungi bre- ak down rock and how bacteria form minerals (see p. 40). Geoscientists and ecologists are seeking out hitherto un- known microbes in rocks in Thuringia’s Hainich National Park and in the Thu- ringian Basin (see p. 36). Microbes living in the soil break down dead wood and other plants, and turn them into valuable humus.