Soil- and enantiomer-specific metabolism of amino acids and their peptides by Antarctic soil microorganisms

Hill, Paul W.; Farrell, Mark; Roberts, Paula; Farrar, John; Grant, Helen; Newsham, Kevin K. ORCID:; Hopkins, David W.; Bardgett, Richard D.; Jones, Davey L.. 2011 Soil- and enantiomer-specific metabolism of amino acids and their peptides by Antarctic soil microorganisms. Soil Biology and Biochemistry, 43 (12). 2410-2416.

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Most nitrogen (N) enters many Arctic and Antarctic soil ecosystems as protein. Soils in these polar environments frequently contain large stocks of proteinaceous organic matter, which has decomposed slowly due to low temperatures. In addition to proteins, considerable quantities of D-amino acids and their peptides enter soil from bacteria and lengthy residence times can lead to racemisation of L-amino acids in stored proteins. It has been predicted that climate warming in polar environments will lead to increased rates of soil organic N turnover (i.e. amino acids and peptides of both enantiomers). However, our understanding of organic N breakdown in these soils is very limited. To address this, we tested the influence of chain length and enantiomeric composition on the rate of breakdown of amino acids and peptides in three contrasting tundra soils formed under the grass, moss or lichen-dominated primary producer communities of Signy Island in the South Orkney Islands. Both D- and L-enantiomers of the amino acid monomer were rapidly mineralized to CO(2) at rates in line with those found for L-amino acids in many other terrestrial ecosystems. In all three soils, L-peptides were decomposed faster than their amino acid monomer, suggesting a different route of microbial assimilation and catabolism. D-peptides followed the same mineralization pattern as L-peptides in the two contrasting soils under grass and lichens, but underwent relatively slow decomposition in the soil underneath moss, which was similar to the soil under the grass. We conclude that the decomposition of peptides of L-amino acids may be widely conserved amongst soil microorganisms, whereas the decomposition of peptides of D-amino acids may be altered by subtle differences between soils. We further conclude that intense competition exists in soil microbial communities for the capture of both peptides and amino acids produced from protein breakdown. (C) 2011 Elsevier Ltd. All rights reserved.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Topics & Objectives 2009 - 2012 > Biogeochemistry
BAS Programmes > Polar Science for Planet Earth (2009 - ) > Ecosystems
UKCEH and CEH Sections/Science Areas: Shore
ISSN: 0038-0717
Additional Keywords: oligopeptide, isomer, dissolved organic nitrogen, DON, carbon cycling, mineralization, 14C, permafrost
NORA Subject Terms: Biology and Microbiology
Ecology and Environment
Date made live: 09 Jan 2012 15:10 +0 (UTC)

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