Solubilização biológica de rocha fosfática por cultivo em estado sólido para produção de fertilizantes ecológicos

The objective of this work was to evaluate the solubilization of phosphorus from a phosphate rock by Aspergillus niger , under solid-state cultivation (SSC) in sugarcane ( Saccharum officinarum ) bagasse, by maximizing the efficiency of citric acid production. The phosphate rock (IPR) chosen for the study is a type of igneous rock with a very low phosphorus solubility, obtained from the Itafos company, in Arraias, in the state of Tocantins, Brazil. The rotatable central composite design (RCCD) was used as a statistical tool to evaluate the effect of the concentrations of the carbon source (sucrose) and of the IPR on the SSC medium as a strategy to improve P solubilization. In the process without the IPR, there was a citric acid production of up to 300 g per kilogram of substrate. The experiments in the RCCD showed that the addition of the IPR affected citric acid production, with values of solubilized P ranging from 1.44 to 2.72 g per kilogram of substrate and of solubilized P yield from 12.96 to 48.94%. The analysis of the solubilized P/sucrose ratio showed favorable conditions for P solubilization and citric acid production. The obtained solubilized P values are promising considering that the IPR has a very low solubilization, with only 8.6% P 2 O 5 . Overall, these findings could contribute to the development of biotechnological processes for producing eco-friendly phosphate fertilizers, as an alternative for a more sustainable agriculture.