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Soil microbial community structure and enzymatic activity along a plant cover gradient in Victoria Land (continental Antarctica)

Soil microbial community structure and enzymatic activity along a plant cover gradient in Victoria Land (continental Antarctica)
Soil microbial community structure and enzymatic activity along a plant cover gradient in Victoria Land (continental Antarctica)

In continental Antarctica, autotrophs are exclusively represented by cyanobacteria, algae, lichens and mosses. Consequently, Antarctic soil communities are expected to be rather simple and primarily dominated by microorganisms. Recently, a change in abundance of mosses and lichens has been observed in continental Antarctica in response to an increase of the active permafrost layer, but the implication of this change to soil micro-organisms remains little known. Here we aim to clarify to what extent the abundance of mosses and lichens affects soil biogeochemistry in Victoria Land, with a particular focus on soil microbial abundance and associated soil enzymatic activity. To achieve this aim, we assessed the structure of soil microbiome and the activity of hydrolytic C, N, and P enzymes along a gradient in soil physico-chemical conditions and plant cover. Moss cover strongly relates to the amount of soil organic carbon (SOC), soil water and nutrient content. Soils with higher content of organic carbon were characterized by higher microbial biomass and showed a relatively higher abundance of fungi as compared to bacteria. More specifically, PLFAs biomarkers for Actinomycetes and Gram-positive bacteria were mainly associated to soils with lower SOC. In order to sustain a higher microbial biomass, total activity of hydrolytic enzymes increased with increasing SOC content. Eco-enzymatic stoichiometry, based on C to P and C to N ratios, indicates a higher investment in N- and P-hydrolytic enzymes (ratio < 1), particularly at low SOC content. Oppositely, an increase in C-hydrolytic enzyme activity (ratio ≈ 1) was observed with increasing accumulation of organic carbon. Such a result seems to indicate a stronger role of soil pH at low SOC on enzymatic stoichiometry (abiotic control) whereas with increasing accumulation of organic matter the enzymatic stoichiometry is more affected by microbial metabolism (biotic control).

Bacteria, Fungi, Mosses, PLFAs, Stoichiometry
0016-7061
144-151
Bragazza, Luca
297b335a-0a17-4c30-afbb-dfc5267f6688
Robroek, Bjorn J.M.
06dcb269-687c-41db-ab73-f61899617f92
Jassey, Vincent E.J.
17b9b576-bb3b-4739-830e-744034e5e24a
Arif, Muhammad Saleem
f1db87cf-b645-4c9b-adcb-78c98dfd468a
Marchesini, Roberta
2022a380-da86-41b3-a58d-1c43591372c3
Guglielmin, M.
0e2f08c9-abc8-4125-8899-f522fd19cd98
Cannone, Nicoletta
83799e92-1cf8-4e6e-84c5-6cf4174f8576
Bragazza, Luca
297b335a-0a17-4c30-afbb-dfc5267f6688
Robroek, Bjorn J.M.
06dcb269-687c-41db-ab73-f61899617f92
Jassey, Vincent E.J.
17b9b576-bb3b-4739-830e-744034e5e24a
Arif, Muhammad Saleem
f1db87cf-b645-4c9b-adcb-78c98dfd468a
Marchesini, Roberta
2022a380-da86-41b3-a58d-1c43591372c3
Guglielmin, M.
0e2f08c9-abc8-4125-8899-f522fd19cd98
Cannone, Nicoletta
83799e92-1cf8-4e6e-84c5-6cf4174f8576

Bragazza, Luca, Robroek, Bjorn J.M., Jassey, Vincent E.J., Arif, Muhammad Saleem, Marchesini, Roberta, Guglielmin, M. and Cannone, Nicoletta (2019) Soil microbial community structure and enzymatic activity along a plant cover gradient in Victoria Land (continental Antarctica). Geoderma, 353, 144-151. (doi:10.1016/j.geoderma.2019.06.033).

Record type: Article

Abstract

In continental Antarctica, autotrophs are exclusively represented by cyanobacteria, algae, lichens and mosses. Consequently, Antarctic soil communities are expected to be rather simple and primarily dominated by microorganisms. Recently, a change in abundance of mosses and lichens has been observed in continental Antarctica in response to an increase of the active permafrost layer, but the implication of this change to soil micro-organisms remains little known. Here we aim to clarify to what extent the abundance of mosses and lichens affects soil biogeochemistry in Victoria Land, with a particular focus on soil microbial abundance and associated soil enzymatic activity. To achieve this aim, we assessed the structure of soil microbiome and the activity of hydrolytic C, N, and P enzymes along a gradient in soil physico-chemical conditions and plant cover. Moss cover strongly relates to the amount of soil organic carbon (SOC), soil water and nutrient content. Soils with higher content of organic carbon were characterized by higher microbial biomass and showed a relatively higher abundance of fungi as compared to bacteria. More specifically, PLFAs biomarkers for Actinomycetes and Gram-positive bacteria were mainly associated to soils with lower SOC. In order to sustain a higher microbial biomass, total activity of hydrolytic enzymes increased with increasing SOC content. Eco-enzymatic stoichiometry, based on C to P and C to N ratios, indicates a higher investment in N- and P-hydrolytic enzymes (ratio < 1), particularly at low SOC content. Oppositely, an increase in C-hydrolytic enzyme activity (ratio ≈ 1) was observed with increasing accumulation of organic carbon. Such a result seems to indicate a stronger role of soil pH at low SOC on enzymatic stoichiometry (abiotic control) whereas with increasing accumulation of organic matter the enzymatic stoichiometry is more affected by microbial metabolism (biotic control).

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Bragazza et al_acceptedMS_Geoder_2019 - Accepted Manuscript
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Accepted/In Press date: 24 June 2019
e-pub ahead of print date: 6 July 2019
Published date: 1 November 2019
Keywords: Bacteria, Fungi, Mosses, PLFAs, Stoichiometry

Identifiers

Local EPrints ID: 432704
URI: http://eprints.soton.ac.uk/id/eprint/432704
ISSN: 0016-7061
PURE UUID: 0e0fdaee-d194-4997-817c-4ccde83e3d20
ORCID for Bjorn J.M. Robroek: ORCID iD orcid.org/0000-0002-6714-0652

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Date deposited: 24 Jul 2019 16:30
Last modified: 07 Oct 2020 06:36

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Contributors

Author: Luca Bragazza
Author: Bjorn J.M. Robroek ORCID iD
Author: Vincent E.J. Jassey
Author: Muhammad Saleem Arif
Author: Roberta Marchesini
Author: M. Guglielmin
Author: Nicoletta Cannone

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