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Abstract Microbial necromass is increasingly recognized as an important fast‐cycling component of the long‐term carbon present in soils. To better understand how fungi and bacteria individually contribute to the decomposition of fungal necromass, three particle sizes (>500, 250–500, and <250 μm) ofHyaloscypha bicolornecromass were incubated in laboratory microcosms inoculated with individual strains of two fungi and two bacteria. Decomposition was assessed after 15 and 28 days via necromass loss, microbial respiration, and changes in necromass pH, water content, and chemistry. To examine how fungal–bacterial interactions impact microbial growth on necromass, single and paired cultures of bacteria and fungi were grown in microplates containing necromass‐infused media. Microbial growth was measured after 5 days through quantitative PCR. Regardless of particle size, necromass colonized by fungi had higher mass loss and respiration than both bacteria and uninoculated controls. Fungal colonization increased necromass pH, water content, and altered chemistry, while necromass colonized by bacteria remained mostly unaltered. Bacteria grew significantly more when co‐cultured with a fungus, while fungal growth was not significantly affected by bacteria. Collectively, our results suggest that fungi act as key early decomposers of fungal necromass and that bacteria may require the presence of fungi to actively participate in necromass decomposition.
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This content will become publicly available on December 20, 2025
From networks to mechanisms: A cross-scale analysis of bacterial - fungal interactions in fungal necromass
Microbial community dynamics are dependent on interactions between the community members, yet studies of interactions across domains and with multiple experimental approaches are lacking. In this study, we explored interactions between bacteria and fungi associated with decaying fungal necromass using both field-based co-occurrence networks and laboratory-based pairwise interactions. The majority of field-derived bacterial-fungal correlations were negative, suggesting a potentially competitive environment within necromass compared to other systems. Laboratory experiments consisted of bacteria most often reducing fungal growth, while the fungal effect on bacterial growth was more varied and dependent on bacterial taxa. However, these interactions were not consistently predicted by field correlations, highlighting a disconnect between field-based and direct experimental approaches. Our findings suggest that using co-occurrence networks alone to predict BFI outcomes could be misleading, emphasizing the need for more comprehensive, multi-method studies to capture the dynamic and context-dependent nature of microbial interactions.
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- Award ID(s):
- 2038293
- PAR ID:
- 10600704
- Publisher / Repository:
- University of Minnesota Graduate School
- Date Published:
- Format(s):
- Medium: X
- Institution:
- University of Minnesota
- Sponsoring Org:
- National Science Foundation
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