# Unveil of the role of fungal taxa in iron(III) reduction in paddy soil

## TL;DR

This study reveals that fungi play a significant role in iron(III) reduction in paddy soil, challenging the focus on bacteria in such processes.

## Contribution

The study identifies 20 genera of iron(III)-reducing fungi and highlights their underestimated role in biogeochemical cycles.

## Key findings

- Fungal iron(III) reduction occurs at high rates even with antibiotics.
- Organic matter type affects fungal iron(III) reduction rates.
- Fungi contribute significantly to iron and carbon cycling in paddy soils.

## Abstract

Hitherto, research on iron(III)-reduction has mainly focused on bacteria rather than fungal communities. To acquire insight into fungi involved in iron(III) reduction, typical organic matters (containing cellulose, glucose, lactate, and acetate) and ferrihydrite were used as electron donors and acceptors, respectively, in the presence of antibiotics. After antibiotic addition, microbial iron(III) reduction was still detected at quite high rates. In comparison, rates of iron(III) reduction were significantly lower in cellulose-amended groups than those with glucose, lactate, and acetate under the antibiotic-added condition. Patterns of intermediate (e.g., acetate, pyruvate, glucose) turnover were markedly different between treatments with and without antibiotics during organic degradation. A total of 20 genera of potential respiratory and fermentative iron(III)-reducing fungi were discovered based on ITS sequencing and genome annotation. This study provided an insight into the diversity of iron(III)-reducing fungi, indicating the underestimated contribution of fungi to iron and the coupled carbon biogeochemical cycling in environments.