Fractionation and Characterization of Fungal And Tree Biopolymers during forest MOS degradation

PI :  Isabelle Ziegler-Devin (EA 4370 Laboratoire d’Etudes et de Recherche sur le Matériau Bois – LERMAB)

Collaborations : Nicolas Brosse (Laboratoire d’Etudes et de Recherche sur le Matériau Bois – LERMAB); Marc Buée, François Maillard, Eric Gelhaye (UMR 1136 Interactions Arbres/Micro-organismes – IAM); Bernd Zeller (UMR 1138 Biogéochimie des Ecosystèmes Forestiers – BEF)

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Context — Fungi have been shown to constitute an important portion of belowground biomass in forest soils (~60–90% of soil microbial biomass in temperate forest ecosystems). Ectomycorrhizal species have been found to dominate fungal communities in temperate and boreal forests. They contribute to lignolytic and fungi necromass degradation and consecutively, they actively work to stabilize carbon from soil organic matter (SOM). Nevertheless, little is known about the degradation of biopolymers constituting necromass and their chemical nature during these processes, and the relative stability or lability of the fungal and plant fractions.

Objectives — A better understanding of dynamic and interaction of both necromass and fungi could improve the prediction of long term soil carbon storage. In order to understand how this composition could influence the rate of decomposition and/or stabilisation of SOM, a combination of physical fractionation and chemical and spectroscopic characterization will be developed to identify chemical composition of separated fractions.

Approaches — Extractibles, hemicelluloses, cellulose, lignine, chitin constituting necromass and fungi will be extracted by chemical methods then quantified mainly by GC/MS; HPLC; SEC; HPAE/PAD. In parallel, Near InfraRed (NIR) and Mid-InfraRed (MIR) spectroscopy techniques will used be to characterize organic material, as wood and leaf litter. Then the models predicting organic compounds (chitin, cellulose, hemicelluloses, and lignin) from NIRS-MIRS spectra will be calibrate and validate using comparative data obtained from previous chemical analyses.

Expected results and impacts — The validation and calibration of performing methods should allow to propose protocols and analysis tools that will benefit to different domains, such as geochemistry, microbiology and wood technology.