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Title: Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

Abstract

The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78°N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy number of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below -10°C. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soilmore » parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface.« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1221483
Report Number(s):
PNNL-SA-110669
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Frontiers in Microbiology, 6:Article No. 399
Additional Journal Information:
Journal Name: Frontiers in Microbiology, 6:Article No. 399
Country of Publication:
United States
Language:
English
Subject:
permafrost; arctic; bacterial communities; Alphaproteobacteria; Cyanobacteria; phototrophic organisms

Citation Formats

Schostag, Morten, Stibal, Marek, Jacobsen, Carsten S., Baelum, Jacob, Tas, Neslihan, Elberling, Bo, Jansson, Janet K., Semenchuk, Phillip, and Prieme, Anders. Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses. United States: N. p., 2015. Web. doi:10.3389/fmicb.2015.00399.
Schostag, Morten, Stibal, Marek, Jacobsen, Carsten S., Baelum, Jacob, Tas, Neslihan, Elberling, Bo, Jansson, Janet K., Semenchuk, Phillip, & Prieme, Anders. Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses. United States. doi:10.3389/fmicb.2015.00399.
Schostag, Morten, Stibal, Marek, Jacobsen, Carsten S., Baelum, Jacob, Tas, Neslihan, Elberling, Bo, Jansson, Janet K., Semenchuk, Phillip, and Prieme, Anders. Thu . "Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses". United States. doi:10.3389/fmicb.2015.00399.
@article{osti_1221483,
title = {Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses},
author = {Schostag, Morten and Stibal, Marek and Jacobsen, Carsten S. and Baelum, Jacob and Tas, Neslihan and Elberling, Bo and Jansson, Janet K. and Semenchuk, Phillip and Prieme, Anders},
abstractNote = {The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78°N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy number of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below -10°C. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soil parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface.},
doi = {10.3389/fmicb.2015.00399},
journal = {Frontiers in Microbiology, 6:Article No. 399},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {4}
}