Tu T. T. N. auteur aut IRD Texier M. auteur aut IRD Krimou R. auteur aut IRD Biron P. auteur aut IRD Collin S. auteur aut IRD Aubry E. auteur aut IRD Mendez-Millan Mercedes auteur aut IRD Anquetil C. auteur aut IRD Kunz C. auteur aut IRD Delarue F. auteur aut IRD Alexis M. A. auteur aut IRD Dupont J. auteur aut IRD text journalArticle eng text/pdf reformatted digital access This work aimed at better documenting the effects of fungal activity on dissolved organic matter (OM) in soils. Dynamics of water-extractable OM (as surrogate for dissolved OM) quantity and chemical quality was monitored during a ca. 6 month microcosm incubation of plant residues in the presence of fungi. Differential 13C-labelling of metabolites vs structural compounds of the incubated residues further allowed clarifying the balance between fungal mineralisation and production of soluble compounds (through biosynthesis and/or decomposition). The fungus Trichoderma harzianum was mainly active during the first weeks of incubation, substantially mineralizing WEOM, preferentially consuming carbohydrates. The fungus induced chemical modification of WEOM, notably selective preservation of lipids and oxidation of lignin moieties. While T. harzianum probably degraded some insoluble structural molecules and produced biomass, these contributions to bulk WEOM appeared minor (when compared with leaching and mineralization), either because non-significant or entering non-extractable carbon pool. Additionally, characterization of control fungus-free microcosms, highlighted the potential role of abiotic processes on WEOM production, including leaching and depolymerisation by extracellular enzymes, notably of carbohydrate rich (insoluble) macromolecules. specialized Dissolved organic matter Fungi Chemical composition Decomposition processes Enzyme activity 13C labelling 068 074 466 117670 [11 p.] 2026 0016-7061 https://www.documentation.ird.fr/hor/fdi:010096283 10.1016/j.geoderma.2025.117670 0016-7061 [F B010096283] https://www.documentation.ird.fr/hor/fdi:010096283 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2026-03/010096283.pdf IRD - Base Horizon / Pleins textes 2026-03-11 2026-03-11 fdi:010096283 fre