Shcheglova N. Application of biogenic surface-active substances and glauconite for enhancement of the efficiency of the preparations of nitrogen-fixing bacteria

The thesis is devoted to the investigation of the influence of biogenic surface-active substances and argillaceous mineral glauconite on the functional activity of nitrogen-fixing microorganisms as well as their use for increasing the efficiency of biopreparations for leguminous and grain crops. The biosurfactants (rhamnolipids, trehalosolipids) were produced, their biological activity towards the bacteria of genera Rhizobium, Sinorhizobium and Enterobacter was studied by the following indices: exopolysaccharide (EPS) synthesis, dehydrogenase activity and cell membrane permeability. It was determined, that glauconite and its mixtures with biosurfactants increase the quantities of nitrogen-fixing bacteria and their EPS synthesis. The germination, biometric indices of seedlings and vegetative mass of plants increased after the treatment of seeds of legumes and spring barley with the solutions of the produced surfactants. The stimulating influence of the biogenic surfactants in composition of biopreparations on the formation of symbiotic and associative systems of microorganisms with plants was determined for the first time. At that the vegetative mass of plants, the nodulation activity of rhizobia, root nodule nitrogen-fixing activity and potential nitrogen-fixing activity in the root zone of barley increased. The dependence of the impact of biogenic surfactants on their nature (rhamnolipids, trehalose lipids) as well as the genera of studied microorganisms zwas shown. The optimum method of application of surfactants in biopreparations was determined - introduction into the nutrient medium for the cultivation of bacteria. The greatest efficiency was showed by the bacterial preparations with application of mixtures of surfactants and glauconite. The use of complex biopreparations will enhance the effectiveness of systems microorganisms-plants, improvement of harvests and production of high-quality agricultural products.