Solubilization of phosphorus from phosphate rocks with Acidithiobacillus thiooxidans following a growing-then-recovery process

• Published in: World journal of microbiology & biotechnology Vol. 34; no. 1; pp. 17 - 10
• Main Authors: Calle-Castañeda, Susana M., Márquez-Godoy, Marco A., Hernández-Ortiz, Juan P.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-01-2018; Springer Nature B.V
• Subjects: Acid production; Applied Microbiology; Bacteria; Bacterial leaching; Biochemistry; Biological activity; Biological effects; Biomedical and Life Sciences; Biomolecules; Biotechnology; Calcite; Cultivation; Environmental Engineering/Biotechnology; Fluorapatite; Fourier transforms; Gypsum; Infrared spectroscopy; Leaching; Life Sciences; Low concentrations; Microbiology; Original Paper; pH effects; Phosphate; Phosphorus; Recovery; Rocks; Solubilization; Tropical environments; Tropical soils; Phosphorus; Bioleaching; Phosphate rock; FTIR; Acidithiobacillus thiooxidans
• ISSN: 0959-3993; 1573-0972
• DOI: 10.1007/s11274-017-2390-7

Phosphorus is an essential nutrient for the synthesis of biomolecules and is particularly important in agriculture, as soils must be constantly supplemented with its inorganic form to ensure high yields and productivity. In this paper, we propose a process to solubilize phosphorus from phosphate rocks, where
Acidithiobacillus thiooxidans
cultures are pre-cultivated to foster the acidic conditions for bioleaching-two-step “growing-then-recovery”-. Our method solubilizes 100% of phosphorus, whereas the traditional process without pre-cultivation—single-step “growing-and-recovery”-results in a maximum of 56% solubilization. As a proof of principle, we demonstrate that even at low concentrations of the phosphate rock, 1% w/v, the bacterial culture is unviable and biological activity is not observed during the single-step process. On the other hand, in our method, the bacteria are grown without the rock, ensuring high acid production. Once pH levels are below 0.7, the mineral is added to the culture, resulting in high yields of biological solubilization. According to the Fourier Transform Infrared Spectroscopy spectrums, gypsum is the dominant phosphate phase after both the single- and two-step methods. However, calcite and fluorapatite, dominant in the un-treated rock, are still present after the single-step, highlighting the differences between the chemical and the biological methods. Our process opens new avenues for biotechnologies to recover phosphorus in tropical soils and in low-grade phosphate rock reservoirs.