Effect of Aspergillus Niger on Weathering of Phosphorite in Laboratorial Conditions
The authors examined the mechanism of weathering of phosphorite by Aspergillus niger in the laboratory. Several strains of phosphate-dissolving fungi were isolated from rhizosphere soils. A strain of stronger phosphate-dissolving fungi was acquired, which was identified as A. niger by the methods of identifying morphology and comparing ITS sequences in Genbank. In liquid culture, incubation in static state, the weathering of apatite with the fungus was done by using the contrast method, namely fungal direct and indirect process. The supernatants collected at different incubation periods were determined in terms of the concentrations of Ca2+, Mg2+, Al3+, Fe3+, and K+ by ICP-OES, and those of H2PO4 -, SO4 2- and Cl- by ion chromatography (Dionex ICS-90). The remaining minerals were micromorphologically analyzed by means of an electron microprobe, and the mineral composition was determined by XRD. The results showed that the direct weathering process was stronger than the indirect one, and that the variation of ion concentrations was a steady increase firstly, and then a smooth state, and finally a drop to the bottom. Kaolinite was weathered first, followed by apatite, illite, and montmorillonite. During the weathering of the minerals, a calcium oxalate in the secondary minerals was produced. This study confirmed organic acid chelation during the microorganism’s weathering process. Based on our experimental results, it is concluded that the mechanical breakage of the mycelium growth, the bio-degradation of extra cellular macromolecules, and the integrated operation of many factors seem to be the reasons for the bio-weathering of minerals.
Aspergillus niger mechanism phosphorite weathering
CHEN Shu CHEN Hai Yan HUANG Sheng
Key Laboratory of Solid Waste Treatment and Resource Recycle,Ministry of Education (SWUST),Mianyang 621010,Sichuan,China
国际会议
2009 International Symposium on Environmental Science and Technology(2009环境科学与技术国际会议)
上海
英文
2273-2279
2009-06-02（万方平台首次上网日期，不代表论文的发表时间）