Advanced

Influence of ammonium on formation of mineral-associated organic carbon by an ectomycorrhizal fungus

Wang, Tao LU ; Tian, Zhaomo LU ; Tunlid, Anders LU and Persson, Per LU (2019) In Applied and Environmental Microbiology 85(10).
Abstract

The interactions between dissolved organic matter (DOM) and mineral particles are critical for the stabilization of soil organic matter (SOM) in terrestrial ecosystems. The processing of DOM by ectomycorrhizal fungi contributes to the formation of mineral-stabilized SOM by two contrasting pathways: the extracellular transformation of DOM (ex vivo pathway) and the secretion of mineral-surface-reactive metabolites (in vivo pathway). In this study, we examined how changes in nitrogen (N) availability affected the formation of mineral-associated carbon (C) from these two pathways. DOM was extracted from forest soils. The processing of this DOM by the ectomycorrhizal fungus Paxillus involutus was examined in laboratory-scale studies with... (More)

The interactions between dissolved organic matter (DOM) and mineral particles are critical for the stabilization of soil organic matter (SOM) in terrestrial ecosystems. The processing of DOM by ectomycorrhizal fungi contributes to the formation of mineral-stabilized SOM by two contrasting pathways: the extracellular transformation of DOM (ex vivo pathway) and the secretion of mineral-surface-reactive metabolites (in vivo pathway). In this study, we examined how changes in nitrogen (N) availability affected the formation of mineral-associated carbon (C) from these two pathways. DOM was extracted from forest soils. The processing of this DOM by the ectomycorrhizal fungus Paxillus involutus was examined in laboratory-scale studies with different levels of ammonium. At low levels of ammonium (i.e., under N-limited conditions), the DOM components were slightly oxidized, and fungal C metabolites with iron-reducing activity were secreted. Ammonium amendments decreased the amount of C metabolites, and no additional oxidation of the organic matter was detected. In contrast, the hydrolytic activity and the secretion of N-containing compounds increased, particularly when high levels of ammonium were added. Under these conditions, C, but not N, limited fungal growth. Although the overall production of mineral-associated organic C was not affected by ammonium concentrations, the observed shifts in the activities of the ex vivo and in vivo pathways affected the composition of organic matter adsorbed onto the mineral particles. Such changes will affect the properties of organic matter-mineral associations and, thus, ultimately, the stabilization of SOM.

(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Decomposition, Ectomycorrhizal fungi, Organic matter-mineral interaction, Soil organic matter
in
Applied and Environmental Microbiology
volume
85
issue
10
publisher
American Society for Microbiology
external identifiers
  • scopus:85065593239
ISSN
0099-2240
DOI
10.1128/AEM.03007-18
language
English
LU publication?
yes
id
d1a98e06-ffae-4967-b4ff-e32c2387f852
date added to LUP
2019-05-22 14:34:21
date last changed
2019-06-19 04:13:11
@article{d1a98e06-ffae-4967-b4ff-e32c2387f852,
  abstract     = {<p>The interactions between dissolved organic matter (DOM) and mineral particles are critical for the stabilization of soil organic matter (SOM) in terrestrial ecosystems. The processing of DOM by ectomycorrhizal fungi contributes to the formation of mineral-stabilized SOM by two contrasting pathways: the extracellular transformation of DOM (ex vivo pathway) and the secretion of mineral-surface-reactive metabolites (in vivo pathway). In this study, we examined how changes in nitrogen (N) availability affected the formation of mineral-associated carbon (C) from these two pathways. DOM was extracted from forest soils. The processing of this DOM by the ectomycorrhizal fungus Paxillus involutus was examined in laboratory-scale studies with different levels of ammonium. At low levels of ammonium (i.e., under N-limited conditions), the DOM components were slightly oxidized, and fungal C metabolites with iron-reducing activity were secreted. Ammonium amendments decreased the amount of C metabolites, and no additional oxidation of the organic matter was detected. In contrast, the hydrolytic activity and the secretion of N-containing compounds increased, particularly when high levels of ammonium were added. Under these conditions, C, but not N, limited fungal growth. Although the overall production of mineral-associated organic C was not affected by ammonium concentrations, the observed shifts in the activities of the ex vivo and in vivo pathways affected the composition of organic matter adsorbed onto the mineral particles. Such changes will affect the properties of organic matter-mineral associations and, thus, ultimately, the stabilization of SOM.</p>},
  articleno    = {e03007-18},
  author       = {Wang, Tao and Tian, Zhaomo and Tunlid, Anders and Persson, Per},
  issn         = {0099-2240},
  keyword      = {Decomposition,Ectomycorrhizal fungi,Organic matter-mineral interaction,Soil organic matter},
  language     = {eng},
  number       = {10},
  publisher    = {American Society for Microbiology},
  series       = {Applied and Environmental Microbiology},
  title        = {Influence of ammonium on formation of mineral-associated organic carbon by an ectomycorrhizal fungus},
  url          = {http://dx.doi.org/10.1128/AEM.03007-18},
  volume       = {85},
  year         = {2019},
}