Isotope Labeling Reveals Complex Microbial Interactions during Agaricus bisporus Compost Colonization
Year: 2026
Type: preprint
Abstract: Microbial interactions strongly influence carbon and nitrogen flows in mushroom compost, yet their functional roles during Agaricus bisporus colonization remain unresolved. We combined PLFA-SIP and nanoSIMS imaging with ITS amplicon sequencing to follow resource flows and microbial activity across spatial scales. Stable-isotope tracers (¹³C- glucose and ¹⁵N-ammonium) revealed that A. bisporus simultaneously facilitates and suppresses bacterial populations: fungal activity increased glucose assimilation by bacteria yet reduced overall bacterial biomass. NanoSIMS visualized nutrient-rich microenvironments along hyphae where bacterial ¹³C and ¹⁵N assimilation was elevated. Sequencing showed the fungal community to comprise essentially two organisms, A. bisporus and Mycothermus thermophilus , which differ approximately elevenfold in their content of the fungal biomarker C18:2ω6,9c. Total fungal PLFA therefore tracks which of the two dominates as much as it tracks fungal biomass. Together these findings reveal coupled fungal–bacterial nutrient processing and show that biomarker-based estimates of fungal biomass require community composition to be known. Multi-scale isotope probing provides a framework for resolving microbial interactions in complex detrital systems. Key Points A. bisporus raises bacterial glucose uptake but lowers bacterial biomass Bacteria near hyphae show elevated 13 C and 15 N uptake at single-cell scale Fungal PLFA reflects the combined signal of fungus identity and biomass Graphic abstract
Institutions: Utrecht University, Netherlands Institute of Ecology
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: green
Award: G4530794220
OpenAlex ID: W7204258632