Overexpression of Na, K-ATPase gene enhanced the weathering ability of Aspergillus niger to wollastonite

Abstract:

[Objective] To investigate and confirm the role of Na, K-ATPase (NKA) of Aspergillus niger in the weathering process of wollastonite, a silicate mineral. [Methods] Wild type Aspergillus niger was used as the original strain to construct high Na, K-ATPase α1 (NKA α1) gene-expressing strain oeNKA. We determined the biomass of oeNKA and the wild strain, pH of the culture medium and Ca²⁺ concentration released from wollastonite at different cultivation time (0, 2, 4 and 6 d). Besides, we also analyzed the mineralogy of the wollastonite residue by X-ray diffraction (XRD) to compare the weathering effect of oeNKA and the wild strain on wollastonite. [Results] The relative expression of NKA α1 and enzyme activity of oeNKA strain was 103 and 1.76 times higher than those of the wild strain, respectively. The biomass and pH of oeNKA had the same variation tendency as the wild strain during the 6-day cultivation. The biomass difference between the wild strain and oeNKA decreased significantly on the 2nd day, and then was gradually narrowed down over time and reached the lowest on the 6th day. Furthermore, the concentration of Ca²⁺ (1011.36±47.78 μg/g) released from wollastonite was about 4 times as that from the wild strain (248.30±25.21 μg/g). Moreover, the XRD pattern also showed that oeNKA exhibited intense effect on wollastonite weathering. [Conclusion] The weathering ability of oeNKA to wollastonite was significantly higher than that of the wild strain, and Na, K-ATPase in Aspergillus niger was actively involved in wollastonite weathering.

Key words:Aspergillus niger;Na, K-ATPase;wollastonite;weathering