N2O fluxes by fungal denitrification, quantification, control and foreseen modelling

Denitrification is one of the main N₂O production processes in soils and can be carried out by bacteria and fungi. Since most fungi lack the enzyme N₂O reductase, N₂O is the major end product (Shoun et al. 1992). So far, reliable methods to quantify fungal contribution to N₂O fluxes from denitrification are lacking, although studies with growth inhibition indicated considerable N₂O production by fungi (Laughlin and Stevens, 2002) and N₂O isotopic signatures differ between bacterial and fungal denitrifiers in pure culture experiments (Rohe et al. 2017; Sutka et al. 2008). However, understanding of fungal denitrification is necessary to improve modelling of N₂O emissions and to develop mitigation strategies.

Thus, a set of isotope and inhibition approaches will be used to evaluate and improve methods to quantify the contribution of fungi to soil-derived N₂O fluxes and unravel their controls. Data will be evaluated using “isotope mapping” approaches (Lewicka-Szczebak et al. 2017) including the calculation tool FRAME (Lewicki et al. 2022). By identifying fungal key players and their regulation, our experimental results will help to develop conceptual approaches of how to integrate fungal denitrification into biogeochemical models.

References: Laughlin and Stevens. 2022. SSAJ 66:1540-1548. Lewicka-Szczebak et al. 2017. Biogeosciences 14:711-732. Lewicki M et al. 2022. PloS one 17:e0277204. Rohe et al. 2014 RCM 31:1297-1312. Shoun et al. 1992. FEMS Microbiology Letters 94:277-281. Sutka et al. 2008. RCM 22:3989-3996.