Biological chlorine cycling in the Arctic Coastal Plain
Biological chlorine cycling in the Arctic Coastal Plain
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DOI：
10.1007/s10533-017-0359-0
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发表时间：
2017-07
期刊：
影响因子：
4
通讯作者：
Jaime E. Zlamal;T. Raab;M. Little;Robert Edwards;D. Lipson
中科院分区：
文献类型：
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作者：
Jaime E. Zlamal;T. Raab;M. Little;Robert Edwards;D. Lipson
本研究探讨了生物氯循环在沿海北极湿苔原土壤。虽然以前的许多氯循环研究都集中在污染的环境中，但现在人们认识到，氯可以在土壤中的无机和有机形式之间自然循环。然而，这些途径以前没有被描述为北极生态系统。我们测量了土壤有机和无机氯池，其特征在于土壤和植物组织与氯K-边X射线吸收近边光谱（Cl-XANES），在实验室培养中测量脱氯率，并分析宏基因组和16 S rRNA基因沿着一个时间序列的植被排水湖泊盆地。土壤有机氯化合物（Clorg）的浓度与有机质含量相关，在较老的土壤中的斜率较陡。Clorg的浓度和化学多样性随着土壤发育而增加，Clorgin年轻的土壤更接近于植被，而较老的土壤具有更复杂和可变的Cl-XANES签名。植物Clorgconcentrations高于以前公布的值，并可以解释快速积累的Clorgin土壤。来自植物的高氯输入率也意味着土壤氯池在土壤发育过程中会发生多次翻转。宏基因组学分析揭示了Clorg合成（卤代过氧化物酶，卤化酶）和分解（还原脱卤酶，卤代酸脱卤酶）的推定基因，源自不同的微生物基因组。许多基因组序列与已知的有机卤化物呼吸（如Dehalococcoides）的密切相似性进行了鉴定，实验室培养证明微生物有机卤化物呼吸体外。这项研究为北极苔原生态系统中复杂和动态的氯循环提供了多条证据。
This study explores biological chlorine cycling in coastal Arctic wet tundra soils. While many previous chlorine-cycling studies have focused on contaminated environments, it is now recognized that chlorine can cycle naturally between inorganic and organic forms in soils. However, these pathways have not previously been described for an Arctic ecosystem. We measured soil organic and inorganic Cl pools, characterized soils and plant tissues with chlorine K-edge X-ray absorption near-edge spectroscopy (Cl-XANES), measured dechlorination rates in laboratory incubations, and analyzed metagenomes and 16S rRNA genes along a chronosequence of revegetated drained lake basins. Concentrations of soil organic chlorinated compounds (Clorg) were correlated with organic matter content, with a steeper slope in older soils. The concentration and chemical diversity of Clorgincreased with soil development, with Clorgin younger soils more closely resembling that of vegetation, and older soils having more complex and variable Cl-XANES signatures. Plant Clorgconcentrations were higher than previously published values, and can account for the rapid accumulation of Clorgin soils. The high rates of Clorginput from plants also implies that soil Clorgpools turn over many times during soil development. Metagenomic analyses revealed putative genes for synthesis (haloperoxidases, halogenases) and breakdown (reductive dehalogenases, halo-acid dehalogenases) of Clorg, originating from diverse microbial genomes. Many genome sequences with close similarity to known organohalide respirers (e.g.Dehalococcoides) were identified, and laboratory incubations demonstrated microbial organohalide respiration in vitro. This study provides multiple lines of evidence for a complex and dynamic chlorine cycle in an Arctic tundra ecosystem.