Różnorodność biologiczna i rola bakterii glebowych w środowisku leśnym

Microorganisms commonly inhabit all environments in which they can survive. The number of bacteria in soil depends on its structure, moisture and nutrient content, and ranges from a few hundred to several thousand per gram of soil. Qualitative and quantitative composition of bacteria mainly depends on physico−chemical agents, soil and vegetation cover, the content of biogenic elements, but also on the salinity and pollution. In the case of forest soils number of bacteria amounts to about 4.8×10 9 per 1 cm 3 of soil. In the rhizosphere, the soil directly surrounding plant roots, there are organisms that affect the biochemical activity of plants. The main representatives of bacteria, which are present in the rhizosphere layer, are species of the genera: Pseudomonas and Bacillus, Acidobacteria that protect plants against attack of pathogens. Soil microorganisms form a symbiosis with vascular plants. Because of their properties, they are effective antagonists against fungi that cause plant diseases (leaf spots, roots and shoot apices disease, as well as rot). This group includes such species as: Sclerotinia sclerotiorum, Botrytis cinerea and Colletotrichum gloeosporioides or the species belonging to Oomycetes, for example Phytophthora and Pythium. Bacteria also protect plants against harmful insects and inhibit the growth of fungal diseases. The beneficial role of bacteria is observed in the development of truffles as well. They are responsible for providing nitrogen to the mycelium forming fruiting bodies. Bacteria improve plant growth and protect their host against drought. Understanding the diversity of bacteria that have important role in the functioning of ecosystems, including forest ecosystems, remains a challenge for microbiologists.