The chemical characteristics of fungal necromass regulate its decomposition dynamics in forest soils and shape the succession and composition of the associated necrobiome.

In forests, a large proportion of the carbon from Soil Organic Matter is incorporated by primary decomposers, in particular fungi. These micro-organisms produce necromass, which is degraded by other soil microbial communities, the secondary decomposers. The cell walls of dead fungal mycelia are made up of different macromolecules rich in carbon and nitrogen, such as chitin and melanin, which are present in varying proportions. The aim of this project is to test the intrinsic chemical parameters of necromass on its decomposition dynamics in a forest soil, and to identify the main microbial actors (bacteria and fungi) that succeed one another during the decomposition of necromass. The decomposition dynamics of two types of fungal necromass, characterised by contrasting levels of melanisation, were measured over a six-month period. The taxonomic composition and temporal dynamics of the microbial communities associated with the fungal necromass were described using a metabarcoding approach and the bacterial and fungal biomasses were estimated using qPCR.