Biossolubilização de fósforo proveniente de rocha fosfática utilizando fungos e bactérias

Abstract

Plants, like every living thing, need nutrients that are one of the determining factors for growth and development, and which in turn are removed from the soil. Phosphorus is an essential element for plants and is present in the soil at low concentrations. In order to meet this need, chemical fertilizers are added, however, one of the main problems regarding the absorption of phosphorus by plants is due to the fact that a large part of the chemical fertilizer is in the immobilized form as insoluble phosphates. Worldwide, more than 99% of phosphate fertilizers are produced from phosphate rock reserves and use of strong inorganic acids (sulfuric acid) to obtain more soluble forms of phosphate, generating by-products that impact the environment. The use of phosphate solubilizing microorganisms (MSF) has been shown to be a promising biotechnological alternative for the production of fertilizers with soluble phosphates from phosphate rock (RF). The objective of this work was to select fungi and bacteria with efficient performance in phosphorus biosolubilization, as well as to evaluate the use of co-cultures in the process and to study the phosphorus biosolubilization process in conical, lift and rotary reactor, analyzing the operational conditions and the organic acids produced throughout the process. For the tests carried out in submerged fermentation using Trichoderma species, it was verified that all presented similar behavior in relation to the analyzed variables (pH, acid production, soluble phosphorus and amount of biomass), and the association (co-culture) of Trichoderma showed to be more efficient, with maximum efficiency achieved of 19.4%. In the tests carried out in solid state fermentation, in a rotary drum type reactor with initial moisture of 55%, the maximum efficiency was 49.6%. The importance of the production of organic acids, the pH value of the medium for the process, as well as the compositions and conditions of growth of the microorganisms were verified, both for the processes using fungi and for which the bacteria were used. In the tests in which the bacteria were the MSF, the species of the genus Bacillus tested had the same solubilizing potential for phosphate rock, when tested alone. In the case of acidophilic bacteria, Acidithiobacillus ferrooxidans presented better results compared to Acidithiobacillus thiooxidans.