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Minerals, microbes and melanin drive differential incorporation of fungal necromass carbon and nitrogen into mineral-associated organic matter

Beidler, Katilyn V. ; Huenupi, Elizabeth ; DeLancey, Lang C. ; Maillard, François LU ; Zhang, Bowen LU orcid ; Persson, Per LU ; Kennedy, Peter G. and Phillips, Richard (2025) In Soil Biology and Biochemistry 208.
Abstract

Despite the importance of mineral-associated organic matter (MAOM) in long-term soil carbon (C) and nitrogen (N) persistence, and the significant contribution of fungal necromass to this pool, the factors controlling the formation of fungal-derived MAOM remain unclear. This study investigated how fungal necromass chemistry, specifically melanin, interacts with soil mineral properties and microbial communities to influence MAOM formation and persistence. We cultured the fungus Hyaloscypha bicolor to produce 13C- and 15N-labeled necromass with varying melanin content (high or low) and incubated it in both live and autoclaved soils collected from six Indiana forests that differed in their clay and iron oxide (FeOx)... (More)

Despite the importance of mineral-associated organic matter (MAOM) in long-term soil carbon (C) and nitrogen (N) persistence, and the significant contribution of fungal necromass to this pool, the factors controlling the formation of fungal-derived MAOM remain unclear. This study investigated how fungal necromass chemistry, specifically melanin, interacts with soil mineral properties and microbial communities to influence MAOM formation and persistence. We cultured the fungus Hyaloscypha bicolor to produce 13C- and 15N-labeled necromass with varying melanin content (high or low) and incubated it in both live and autoclaved soils collected from six Indiana forests that differed in their clay and iron oxide (FeOx) content. After 38 days, we found that seven times more fungal-derived N was incorporated into MAOM than fungal-derived C, with fungal N comprising 20 % of the MAOM-N pool. Low melanin necromass formed more MAOM-C than high melanin necromass, although site-level differences in overall MAOM formation were substantial. Soil clay and FeOx content were strong predictors of MAOM formation, explaining ∼60 % and ∼68 % of the variation in MAOM-C and MAOM-N, respectively. However, microbial communities also significantly influenced MAOM formation, with MAOM-C formation enhanced and MAOM-N formation reduced in autoclaved soils. Furthermore, the relative abundance of fungal saprotrophs was negatively correlated, and bacterial richness was positively correlated with MAOM formation, and these relationships were influenced by necromass melanin content. Collectively, this study reveals that microbial communities and soil properties interactively mediate the incorporation of fungal necromass C and N into MAOM, with microbes differentially influencing C and N incorporation, and these processes being further modulated by necromass melanization.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Fungal necromass, Iron oxide, Melanin, Mineral-associated soil organic matter
in
Soil Biology and Biochemistry
volume
208
article number
109843
publisher
Elsevier
external identifiers
  • scopus:105005182375
ISSN
0038-0717
DOI
10.1016/j.soilbio.2025.109843
language
English
LU publication?
yes
id
68c79d1d-82ab-4790-ac41-2d22b9ed2574
date added to LUP
2025-07-16 14:53:15
date last changed
2025-07-16 14:54:26
@article{68c79d1d-82ab-4790-ac41-2d22b9ed2574,
  abstract     = {{<p>Despite the importance of mineral-associated organic matter (MAOM) in long-term soil carbon (C) and nitrogen (N) persistence, and the significant contribution of fungal necromass to this pool, the factors controlling the formation of fungal-derived MAOM remain unclear. This study investigated how fungal necromass chemistry, specifically melanin, interacts with soil mineral properties and microbial communities to influence MAOM formation and persistence. We cultured the fungus Hyaloscypha bicolor to produce <sup>13</sup>C- and <sup>15</sup>N-labeled necromass with varying melanin content (high or low) and incubated it in both live and autoclaved soils collected from six Indiana forests that differed in their clay and iron oxide (FeOx) content. After 38 days, we found that seven times more fungal-derived N was incorporated into MAOM than fungal-derived C, with fungal N comprising 20 % of the MAOM-N pool. Low melanin necromass formed more MAOM-C than high melanin necromass, although site-level differences in overall MAOM formation were substantial. Soil clay and FeOx content were strong predictors of MAOM formation, explaining ∼60 % and ∼68 % of the variation in MAOM-C and MAOM-N, respectively. However, microbial communities also significantly influenced MAOM formation, with MAOM-C formation enhanced and MAOM-N formation reduced in autoclaved soils. Furthermore, the relative abundance of fungal saprotrophs was negatively correlated, and bacterial richness was positively correlated with MAOM formation, and these relationships were influenced by necromass melanin content. Collectively, this study reveals that microbial communities and soil properties interactively mediate the incorporation of fungal necromass C and N into MAOM, with microbes differentially influencing C and N incorporation, and these processes being further modulated by necromass melanization.</p>}},
  author       = {{Beidler, Katilyn V. and Huenupi, Elizabeth and DeLancey, Lang C. and Maillard, François and Zhang, Bowen and Persson, Per and Kennedy, Peter G. and Phillips, Richard}},
  issn         = {{0038-0717}},
  keywords     = {{Fungal necromass; Iron oxide; Melanin; Mineral-associated soil organic matter}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Soil Biology and Biochemistry}},
  title        = {{Minerals, microbes and melanin drive differential incorporation of fungal necromass carbon and nitrogen into mineral-associated organic matter}},
  url          = {{http://dx.doi.org/10.1016/j.soilbio.2025.109843}},
  doi          = {{10.1016/j.soilbio.2025.109843}},
  volume       = {{208}},
  year         = {{2025}},
}