Cell-wall polysaccharides play an important role in decay resistance of Sphagnum and actively depressed decomposition in vitro

T. Hajek, S. Ballance, J. Limpens, J.T.A. Verhoeven, M.J. Zijlstra

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Abstract

Sphagnum-dominated peatlands head the list of ecosystems with the largest known reservoirs of organic carbon (C). The bulk of this C is stored in decomposition-resistant litter of one bryophyte genus: Sphagnum. Understanding how Sphagnum litter chemistry controls C mineralization is essential for understanding potential interactions between environmental changes and C mineralization in peatlands. We aimed to separate the effects of phenolics from structural polysaccharides on decay of Sphagnum. Wemeasured aerobic microbial respiration of different moss litter types in a lab. We used chemical treatments to step-wise remove the chemical compounds thought to be important in decay-resistance in three taxonomically distant moss genera. We also focused on the effect of Sphagnum-specific cell-wall pectin-like polysaccharides (sphagnan) on C and N mineralization. Removing polymeric lignin-like phenolics had only negligible effects on C mineralization of Sphagnum litter, but increased mineralization of two other bryophyte genera, suggesting a minor role of these phenolics in decay resistance of Sphagnum but a major role of cell-wall polysaccharides. Carboxyl groups of pectin-like polysaccharides represented a C-source in non-Sphagnum litters but resisted decay in Sphagnum. Finally, isolated sphagnan did not serve as C-source but inhibited C and N mineralization instead, reminiscent of the effects reported for phenolics in other ecosystems. Our results emphasize the role of polysaccharides in resistance to, and active inhibition of, microbial mineralization in Sphagnum-dominated litter. As the polysaccharides displayed decay-inhibiting properties hitherto associated with phenolics (lignin, polyphenols), it raises the question if polysaccharide- dominated litter also shares similar environmental controls on decomposition, such as temperature or nutrient and water availability
Original languageEnglish
Pages (from-to)45-57
JournalBiogeochemistry
Volume103
Issue number1-3
DOIs
Publication statusPublished - 2011

Fingerprint

polysaccharide
Polysaccharides
decomposition
mineralization
litter
Decomposition
Lignin
Ecosystems
bryophyte
peatland
moss
lignin
Chemical compounds
Polyphenols
Organic carbon
chemical compound
ecosystem
Nutrients
nutrient availability
water availability

Keywords

  • mild acid-hydrolysis
  • carbon accumulation
  • oxidation-products
  • peat bogs
  • papillosum
  • holocellulose
  • bryophytes
  • peatlands
  • chemistry
  • residues

Cite this

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title = "Cell-wall polysaccharides play an important role in decay resistance of Sphagnum and actively depressed decomposition in vitro",
abstract = "Sphagnum-dominated peatlands head the list of ecosystems with the largest known reservoirs of organic carbon (C). The bulk of this C is stored in decomposition-resistant litter of one bryophyte genus: Sphagnum. Understanding how Sphagnum litter chemistry controls C mineralization is essential for understanding potential interactions between environmental changes and C mineralization in peatlands. We aimed to separate the effects of phenolics from structural polysaccharides on decay of Sphagnum. Wemeasured aerobic microbial respiration of different moss litter types in a lab. We used chemical treatments to step-wise remove the chemical compounds thought to be important in decay-resistance in three taxonomically distant moss genera. We also focused on the effect of Sphagnum-specific cell-wall pectin-like polysaccharides (sphagnan) on C and N mineralization. Removing polymeric lignin-like phenolics had only negligible effects on C mineralization of Sphagnum litter, but increased mineralization of two other bryophyte genera, suggesting a minor role of these phenolics in decay resistance of Sphagnum but a major role of cell-wall polysaccharides. Carboxyl groups of pectin-like polysaccharides represented a C-source in non-Sphagnum litters but resisted decay in Sphagnum. Finally, isolated sphagnan did not serve as C-source but inhibited C and N mineralization instead, reminiscent of the effects reported for phenolics in other ecosystems. Our results emphasize the role of polysaccharides in resistance to, and active inhibition of, microbial mineralization in Sphagnum-dominated litter. As the polysaccharides displayed decay-inhibiting properties hitherto associated with phenolics (lignin, polyphenols), it raises the question if polysaccharide- dominated litter also shares similar environmental controls on decomposition, such as temperature or nutrient and water availability",
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author = "T. Hajek and S. Ballance and J. Limpens and J.T.A. Verhoeven and M.J. Zijlstra",
year = "2011",
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Cell-wall polysaccharides play an important role in decay resistance of Sphagnum and actively depressed decomposition in vitro. / Hajek, T.; Ballance, S.; Limpens, J.; Verhoeven, J.T.A.; Zijlstra, M.J.

In: Biogeochemistry, Vol. 103, No. 1-3, 2011, p. 45-57.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Cell-wall polysaccharides play an important role in decay resistance of Sphagnum and actively depressed decomposition in vitro

AU - Hajek, T.

AU - Ballance, S.

AU - Limpens, J.

AU - Verhoeven, J.T.A.

AU - Zijlstra, M.J.

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AB - Sphagnum-dominated peatlands head the list of ecosystems with the largest known reservoirs of organic carbon (C). The bulk of this C is stored in decomposition-resistant litter of one bryophyte genus: Sphagnum. Understanding how Sphagnum litter chemistry controls C mineralization is essential for understanding potential interactions between environmental changes and C mineralization in peatlands. We aimed to separate the effects of phenolics from structural polysaccharides on decay of Sphagnum. Wemeasured aerobic microbial respiration of different moss litter types in a lab. We used chemical treatments to step-wise remove the chemical compounds thought to be important in decay-resistance in three taxonomically distant moss genera. We also focused on the effect of Sphagnum-specific cell-wall pectin-like polysaccharides (sphagnan) on C and N mineralization. Removing polymeric lignin-like phenolics had only negligible effects on C mineralization of Sphagnum litter, but increased mineralization of two other bryophyte genera, suggesting a minor role of these phenolics in decay resistance of Sphagnum but a major role of cell-wall polysaccharides. Carboxyl groups of pectin-like polysaccharides represented a C-source in non-Sphagnum litters but resisted decay in Sphagnum. Finally, isolated sphagnan did not serve as C-source but inhibited C and N mineralization instead, reminiscent of the effects reported for phenolics in other ecosystems. Our results emphasize the role of polysaccharides in resistance to, and active inhibition of, microbial mineralization in Sphagnum-dominated litter. As the polysaccharides displayed decay-inhibiting properties hitherto associated with phenolics (lignin, polyphenols), it raises the question if polysaccharide- dominated litter also shares similar environmental controls on decomposition, such as temperature or nutrient and water availability

KW - mild acid-hydrolysis

KW - carbon accumulation

KW - oxidation-products

KW - peat bogs

KW - papillosum

KW - holocellulose

KW - bryophytes

KW - peatlands

KW - chemistry

KW - residues

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DO - 10.1007/s10533-010-9444-3

M3 - Article

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JO - Biogeochemistry

JF - Biogeochemistry

SN - 0168-2563

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