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Appl Environ Microbiol. 2016 Oct 27;82(22):6518-6530. Print 2016 Nov 15.

Long-Term Warming Alters Carbohydrate Degradation Potential in Temperate Forest Soils.

Author information

1
Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, Massachusetts, USA.
2
Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA.
3
Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, Massachusetts, USA Department of Biology, University of Massachusetts, Amherst, Massachusetts, USA.
4
Department of Natural Resources and the Environment, University of New Hampshire, Durham, New Hampshire, USA.
5
The Ecosystems Center, Marine Biological Laboratories, Woods Hole, Massachusetts, USA.
6
Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, Massachusetts, USA Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA deangelis@microbio.umass.edu.

Abstract

As Earth's climate warms, soil carbon pools and the microbial communities that process them may change, altering the way in which carbon is recycled in soil. In this study, we used a combination of metagenomics and bacterial cultivation to evaluate the hypothesis that experimentally raising soil temperatures by 5°C for 5, 8, or 20 years increased the potential for temperate forest soil microbial communities to degrade carbohydrates. Warming decreased the proportion of carbohydrate-degrading genes in the organic horizon derived from eukaryotes and increased the fraction of genes in the mineral soil associated with Actinobacteria in all studies. Genes associated with carbohydrate degradation increased in the organic horizon after 5 years of warming but had decreased in the organic horizon after warming the soil continuously for 20 years. However, a greater proportion of the 295 bacteria from 6 phyla (10 classes, 14 orders, and 34 families) isolated from heated plots in the 20-year experiment were able to depolymerize cellulose and xylan than bacterial isolates from control soils. Together, these findings indicate that the enrichment of bacteria capable of degrading carbohydrates could be important for accelerated carbon cycling in a warmer world.

IMPORTANCE:

The massive carbon stocks currently held in soils have been built up over millennia, and while numerous lines of evidence indicate that climate change will accelerate the processing of this carbon, it is unclear whether the genetic repertoire of the microbes responsible for this elevated activity will also change. In this study, we showed that bacteria isolated from plots subject to 20 years of 5°C of warming were more likely to depolymerize the plant polymers xylan and cellulose, but that carbohydrate degradation capacity is not uniformly enriched by warming treatment in the metagenomes of soil microbial communities. This study illustrates the utility of combining culture-dependent and culture-independent surveys of microbial communities to improve our understanding of the role changing microbial communities may play in soil carbon cycling under climate change.

PMID:
27590813
PMCID:
PMC5086546
DOI:
10.1128/AEM.02012-16
[Indexed for MEDLINE]
Free PMC Article

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