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Microbiome. 2019 Feb 20;7(1):29. doi: 10.1186/s40168-019-0643-4.

Genomic and metatranscriptomic analyses of carbon remineralization in an Antarctic polynya.

Author information

1
Geologic Environment Research Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, 34132, Republic of Korea.
2
Department of Microbiology, Chungbuk National University, Cheongju, 28644, Republic of Korea.
3
Division of Polar Ocean Environment, Korea Polar Research Institute, Incheon, 21990, Republic of Korea.
4
Department of Biology, Jeju National University, Jeju, 63243, Republic of Korea.
5
Department of Microbial Ecology, University of Vienna, 1090, Vienna, Austria.
6
Research Group of Gut Microbiome, Korea Food Research Institute, Sungnam, 13539, Republic of Korea.
7
Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
8
Department of Biological Sciences, Inha University, Incheon, 22212, Republic of Korea.
9
Department of Microbiology, Cornell University, Ithaca, NY, 14853-8101, USA.
10
Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, 03550, Alicante, Spain.
11
Department of Marine Science and Convergence Engineering, Hanyang University ERICA Campus, Ansan, 15588, Republic of Korea.
12
Department of Microbiology, Chungbuk National University, Cheongju, 28644, Republic of Korea. rhees@chungbuk.ac.kr.

Abstract

BACKGROUND:

Polynyas in the Southern Ocean are regions of intense primary production, mainly by Phaeocystis antarctica. Carbon fixed by phytoplankton in the water column is transferred to higher trophic levels, and finally, to the deep ocean. However, in the Amundsen Sea, most of this organic carbon does not reach the sediment but is degraded in the water column due to high bacterial heterotrophic activity.

RESULTS:

We reconstructed 12 key bacterial genomes from different phases of bloom and analyzed the expression of genes involved in organic carbon remineralization. A high correlation of gene expression between the peak and decline phases was observed in an individual genome bin-based pairwise comparison of gene expression. Polaribacter belonging to Bacteroidetes was found to be dominant in the peak phase, and its transcriptional activity was high (48.9% of the total mRNA reads). Two dominant Polaribacter bins had the potential to utilize major polymers in P. antarctica, chrysolaminarin and xylan, with a distinct set of glycosyl hydrolases. In the decline phase, Gammaproteobacteria (Ant4D3, SUP05, and SAR92), with the potential to utilize low molecular weight-dissolved organic matter (LMW-DOM) including compatible solutes, was increased. The versatility of Gammaproteobacteria may contribute to their abundance in organic carbon-rich polynya waters, while the SAR11 clade was found to be predominant in the sea ice-covered oligotrophic ocean. SAR92 clade showed transcriptional activity for utilization of both polysaccharides and LMW-DOM; this may account for their abundance both in the peak and decline phases. Ant4D3 clade was dominant in all phases of the polynya bloom, implicating the crucial roles of this clade in LMW-DOM remineralization in the Antarctic polynyas.

CONCLUSIONS:

Genomic reconstruction and in situ gene expression analyses revealed the unique metabolic potential of dominant bacteria of the Antarctic polynya at a finer taxonomic level. The information can be used to predict temporal community succession linked to the availability of substrates derived from the P. antarctica bloom. Global warming has resulted in compositional changes in phytoplankton from P. antarctica to diatoms, and thus, repeated parallel studies in various polynyas are required to predict global warming-related changes in carbon remineralization.

KEYWORDS:

Carbon remineralization; Genomics; Metatranscriptomics; Polynya

PMID:
30786927
PMCID:
PMC6383258
DOI:
10.1186/s40168-019-0643-4
[Indexed for MEDLINE]
Free PMC Article

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