Woodchip bioreactors are a promising approach to remove nitrate from agricultural drainage systems; however, their low removal efficiency at cold temperatures remains a significant challenge. Here we analyzed the efficacy of fungal inoculation to enhance nitrate removal in woodchip bioreactor microcosms under cold conditions. Among the cold-adapted, nitrate-reducing, and cellulose-degrading fungi previously isolated from soil, we identified Linnemannia hyaline strain SCG-10 as the fastest nitrate reducer. Inoculation of this fungal strain enhanced the rates of nitrate reduction, N2 production, and dissolved organic carbon production in woodchip bioreactor microcosms at 5 °C. Production of N2O was minor (<1%) in this study most likely due to the enhanced activity of N2O reducers by labile carbon. Quantitative PCR for nitrogen cycle-related genes showed the active transcription of both fungal and bacterial denitrification genes. These results suggest that inoculating cold-adapted, nitrate-reducing, and cellulose-degrading fungi is a promising approach to remove nitrate from agricultural fields under cold conditions.
Bibliographical noteFunding Information:
We thank Hao Wang for the technical assistance with the NiCE chip. We also thank Dr. Brandy Toner at the University of Minnesota for her support and encouragement to complete this study and Dr. Gary Feyereisen at the USDA-ARS for his help collecting woodchip samples. This research was supported by the MnDRIVE Initiative of the University of Minnesota . AD was supported by the Saudi Arabian Cultural Mission Scholarship and the Minnesota Mycological Society Scholarship.
© 2022 Elsevier Ltd
- Quantitative PCR
- Woodchip bioreactor