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Fungus-initiated catalytic reactions at hyphal-mineral interfaces drive iron redox cycling and biomineralization

2019-07-05 185

     The ability of fungi to weather a wide range of minerals influences plant nutrition and enhances global biogeochemical cycles of life-essential elements. The fungus-mineral interface plays a key role in weathering, but the specific mechanisms underlying these processes remain poorly understood. Here, we examined fungal-mineral weathering using hematite and Trichoderma guizhouense. We showed that hematite dissolution increased over cultivation time, with the formation of secondary minerals up to ~3000 μm-2 at the interfaces after 66 h cultivation. Of the hematite associated with hyphae, approximately 15% was converted to the secondary mineral ferrihydrite. Importantly, superoxide radicals were detected at the hyphal tips and along the whole hyphae. During cultivation, a high concentration (~1000 nM) of hydroxyl radical was also detected. Synchrotron radiation based spectromicroscopies at fungus-mineral interfaces suggest that fungus hyphae alter the local redox state of iron and thus are redox-active. These findings indicate that fungus-initiated catalytic reactions occur at hyphal-mineral interfaces, in view of the fact that superoxide does not diffuse far from the site of formation. Furthermore, these results also suggest that the catalytic reactions may serve as a new strategy for microbial iron uptake. Together, these findings constitute a significant step forward in understanding the ways that fungi make minerals available to biological systems.

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Figure 1. Fungus-initiated catalytic reactions at hyphal-mineral interfaces

This work was supported by the State Key Program of the National Natural Science Foundation of China (41830859) and the National Natural Science Foundation of China (41371248). One part of experiments was conducted at the BL14W, BL08U1, BL15U, and BL01B beamlines in the Shanghai Synchrotron Radiation Facility (SSRF), China.

Yu, G.H.*, Z.L. Chi, H. H. Teng, H.L. Dong, A. Kappler, M.R. Gillings, M.L. Polizzotto, C.Q. Liu, Y.G. Zhu*. Fungus-initiated catalytic reactions at hyphal-mineral interfaces drive iron redox cycling and biomineralization. Geochimica et Cosmochimica Acta, 2019, Doi: 10.1016/j.gca.2019.06.029

Paper link: 

https://doi.org/10.1016/j.gca.2019.06.029