Redox of Fungal Multicopper Oxidase: A Potential Driving Factor for the Silicate Mineral Weathering

Abstract

Microbial mineral weathering is ubiquitous in nature, but research related to the direct effect of oxidoreductase (e.g., fungal multicopper oxidase) on silicate mineral weathering is rare. This study uses genetic engineering technologies of heterologous expression and gene overexpression and electrochemical methods to examine the effects of multicopper oxidase (McoA) and its gene (mcoA) of Aspergillus niger in the weathering of K⁺-bearing silicate minerals (KBS). In the experiment of weathering KBS, the mcoA-overexpressed strain showed higher K⁺-release ability than the wild-type strain, and the heterologous-expressed McoA demonstrated a direct potential to weather KBS and release K⁺. The electrochemical results showed that the reduction potential of McoA was 0.302 V, and doubled the current of the KBS-modified electrode, meaning that McoA can enhance the electricity transfer in the experiment of weathering KBS. This study confirmed that McoA of A. niger can directly participate in the weathering of silicate minerals, which promotes electron transport at the instable edge of minerals to accelerate mineral weathering. The study will enable greater understanding of the role of oxidoreductase in the biochemical weathering of silicate minerals and identify a possible way to improve the microbial weathering capacity on minerals by genetic engineering manipulation.

Keywords:

• Aspergillus niger
• K⁺-bearing silicates
• McoA
• mechanism of weathering

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Additional information

Funding

This work was supported by the Key Project of Natural Science Research in Colleges and Universities in Jiangsu Province [grant number 16KJA180003]; the National Natural Science Foundation of China [grant number 41772360], [grant number 41173091]; and the Priority Academic Program Development of Jiangsu Higher Education Institutions.