The ability of fungi to withstand 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.

Researchers from Tianjin University’s School of Surface-Earth System Science examined fungal-mineral weathering using hematite and Trichoderma guizhouense. Their study showed that hematite dissolution increased over cultivation time, with the formation of secondary minerals up to ~3000 μm-2 at the interfaces after 66 hours of 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, since 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.

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

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

By the Institute of Surface-Earth System Science

Editors: Eva Yin & Doris Harrington