磷矿石的微生物风化作用——以一株黑曲霉(Aspergillus niger)为例

The role of microorganism in the weathering of phosphorite rock: A case study of Aspergillus niger strain

以直接和间接作用的方式研究培养基中黑曲霉Aspergillus niger对磷矿粉的风化作用。在装有100目磷矿石粉的液体培养基中接入该菌研究其对磷矿石粉的直接风化作用;同时将装有100目磷矿石粉的透析袋放入液体培养基中再接入该菌研究其对磷矿石粉的间接风化作用。按不同时间取培养液上清液,用电感耦合等离子体-发射光谱仪测定Ca2+、Mg2+、Al3+、Fe3+、K+和Mn2+浓度,用离子色谱法测定H2PO4-、SO42-和Cl-浓度。此外,黑曲霉风化作用后的矿物残渣用电子探针作表面微观形态分析和XRD矿物物相分析。结果表明:黑曲霉对磷矿石粉风化作用的直接作用强度大于间接作用;黑曲霉可风化磷矿石粉,但对矿粉中不同矿物的风化强度不同,风化过程中形成次生矿物水草酸钙。提出黑曲霉对磷矿石的风化作用源自黑曲霉生长导致的机械破坏作用、胞外分泌物的生化降解作用以及多种因素之间的协同作用。

The authors have examined the microbiological weathering effect of phosphorite by using Aspergillus niger strain as an example. In liquid culture, incubation in static state, the weathering ofapatite with the fungus was done by using the contrast method： apatite powder （100 mesh） was put in liquid culture medium in a flask, the medium was autoclaved, followed by fungus inoculation for the study of direct weathering process; a dialysis bag with apatite powder （100 mesh） was put in the liquid culture medium in the flask, the medium was autoclaved, followed by fungus inoculation so as to study the indirect weathering process. The supernatants collected at different incubation periods were determined in terms of the concentrations of Ca^2＋, Mg^2＋, Al^3＋, Fe^3＋, K^＋ and Mn^2＋ by ICP-OES, and those of H2PO4, SO4^2- and Cl by ion chromatography. 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. 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 extracellular macromolecules, and the integrated operation of many factors seem to be the reasons for the bio-weathering of minerals.