Silva Ubiana de Cássia, Mendes Gilberto de Oliveira, Silva Nina Morena R M, Duarte Josiane Leal, Silva Ivo Ribeiro, Tótola Marcos Rogério, Costa Maurício Dutra
Departamento de Microbiologia, Universidade Federal de Viçosa, Viçosa, MG, Brasil.
Departamento de Solos, Universidade Federal de Viçosa, Viçosa, MG, Brasil; Instituto de Ciências Agrárias, Universidade Federal de Uberlândia, Monte Carmelo, MG, Brasil.
PLoS One. 2014 Oct 13;9(10):e110246. doi: 10.1371/journal.pone.0110246. eCollection 2014.
P-solubilizing microorganisms are a promising alternative for a sustainable use of P against a backdrop of depletion of high-grade rock phosphates (RPs). Nevertheless, toxic elements present in RPs, such as fluorine, can negatively affect microbial solubilization. Thus, this study aimed at selecting Aspergillus niger mutants efficient at P solubilization in the presence of fluoride (F-). The mutants were obtained by exposition of conidia to UV light followed by screening in a medium supplemented with Ca3(PO4)2 and F-. The mutant FS1-555 showed the highest solubilization in the presence of F-, releasing approximately 70% of the P contained in Ca3(PO4)2, a value 1.7 times higher than that obtained for the wild type (WT). The mutant FS1-331 showed improved ability of solubilizing fluorapatites, increasing the solubilization of Araxá, Catalão, and Patos RPs by 1.7, 1.6, and 2.5 times that of the WT, respectively. These mutants also grew better in the presence of F-, indicating that mutagenesis allowed the acquisition of F- tolerance. Higher production of oxalic acid by FS1-331 correlated with its improved capacity for RP solubilization. This mutant represents a significant improvement and possess a high potential for application in solubilization systems with fluoride-rich phosphate sources.
在高品位磷矿石（RPs）枯竭的背景下，解磷微生物是可持续利用磷的一种有前途的替代方法。然而，RPs中存在的有毒元素，如氟，会对微生物解磷产生负面影响。因此，本研究旨在筛选出在氟化物（F-）存在下高效解磷的黑曲霉突变体。通过将分生孢子暴露于紫外线下，然后在添加了Ca3(PO4)2和F-的培养基中进行筛选，获得了这些突变体。突变体FS1-555在F-存在下表现出最高的解磷能力，释放了Ca3(PO4)2中约70%的磷，这一数值比野生型（WT）高出1.7倍。突变体FS1-331表现出增强的氟磷灰石溶解能力，使阿拉萨、卡塔朗和帕托斯RPs的溶解量分别比WT提高了1.7、1.6和2.5倍。这些突变体在F-存在下也生长得更好，表明诱变使它们获得了耐F-能力。FS1-331较高的草酸产量与其提高的RPs溶解能力相关。该突变体代表了显著的改进，在富含氟化物的磷源溶解系统中具有很高的应用潜力。
