Fungal biopolymers as carbon-sequestration bridging agents in soil

Overview

Soil fungi produce recalcitrant biopolymeric materials that can serve as a stable matrix to preserve organic carbon sequestered within soil aggregates during periods of low primary production, including between growing seasons and during droughts. This research platform investigates the identities, variability, and lifetimes of these fungal biopolymers to accelerate the evaluation of novel fungal strains for soil carbon-sequestration potential. By establishing hydrolytic resistance as a proxy assay for recalcitrant fungal material, the work enables rapid initial screening of candidate species, strengthening models of carbon cycling by the soil microbiome.

Technical specifications

Core approach:

• Soil incubation experiments with fungal necromass to track degradation kinetics and isolate recalcitrant residues
• Stepwise hydrolysis procedures applied with increasing aggressiveness to quantify resistant material
• Analytical characterization using GCMS (gas chromatography–mass spectrometry) and FTIR (Fourier-transform infrared spectroscopy) to determine biochemical composition and relative reactivity
• Identification of stable N-rich residues dominated by amide and C-O bond-containing material, consistent with cross-linked peptidoglycan cell wall structures

Proof-of-concept findings:

• Approximately 75–80% of Fusarium aveneceum necromass organic carbon degraded within one week
• Approximately 10% of organic carbon persisted beyond 50 days, indicating a stable recalcitrant fraction
• Reactive portion characterized as rich in glucosamine (chitin monomer) and lipids; stable residue rich in amide and C-O bonds
• Ghost structures resembling emptied cells observed in residues, supporting the cell wall material hypothesis

Candidate sourcing:

• Fungal species associated with agricultural soils and plants
• Potential collaborators include Valent and the International Culture Collection of VA Mycorrhizal Fungi

Technology readiness level

The concept has been validated through laboratory proof-of-concept soil incubations demonstrating measurable fractions of recalcitrant fungal biopolymers with extended lifetimes. Current work focuses on characterizing the degradation-resistant material across multiple fungal species, quantifying species-dependent variability in biopolymer concentration, and assessing contributions to the broader soil organic carbon pool. The hydrolytic resistance proxy assay is positioned as a rapid screening tool to streamline evaluation of new fungal candidates for carbon-sequestration applications. Further validation through expanded species testing and biochemical characterization is ongoing.