Departamento de Materiales y Minerales, Facultad de Minas, Universidad Nacional de Colombia-Medellín, Calle 75 # 79A-51, Bloque M17, Medellín, Colombia.
Institute for Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA.
World J Microbiol Biotechnol. 2017 Dec 29;34(1):17. 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.
磷是生物分子合成的必需营养物质，在农业中尤为重要，因为必须不断向土壤补充其无机形式，以确保高产量和生产力。在本文中，我们提出了一种从磷矿中溶解磷的方法，该方法预先培养氧化亚铁硫杆菌培养物，以促进生物浸出的酸性条件——两步法“生长-然后回收”。我们的方法可溶解 100%的磷，而传统的无预培养的单一“生长-回收”法最多可溶解 56%的磷。作为原理的证明，我们证明了即使在低浓度的磷矿（1%w/v）下，细菌培养物也无法存活，并且在单一步骤过程中不会观察到生物活性。另一方面，在我们的方法中，细菌在没有岩石的情况下生长，从而确保了高酸的产生。一旦 pH 值低于 0.7，就将矿物质添加到培养物中，从而实现高生物溶解产量。根据傅里叶变换红外光谱谱图，在单一和两步法之后，石膏都是主要的磷相。然而，在单一步骤之后，仍然存在处理过的岩石中占主导地位的方解石和氟磷灰石，这突出了化学和生物方法之间的差异。我们的方法为生物技术在热带土壤和低品位磷矿储层中回收磷开辟了新途径。
