Intensive cryptic microbial iron cycling in the low iron water column of the meromictic Lake Cadagno
Intensive cryptic microbial iron cycling in the low iron water column of the meromictic Lake Cadagno
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DOI：
10.1111/1462-2920.13587
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发表时间：
2016-12-01
影响因子：
5.1
通讯作者：
Kuypers, Marcel M. M.
中科院分区：
文献类型：
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作者：
Berg, Jasmine S.;Michellod, Dolma;Kuypers, Marcel M. M.
铁的氧化还原反应在碳矿化中起着重要作用，支持了富含铁的陆地和水生沉积物中的大型微生物群落。具有极低铁浓度的分层水柱在全球范围内广泛存在，但这些系统中的微生物铁循环在很大程度上被忽视。我们发现的证据出乎意料的高铁周转率在低（1-2 μ mol.L（-1））铁沃茨的湖Cadagno。光依赖性，生物铁氧化率（1.4-13.8 μ mol.l（-1）.d（-1））甚至高于在含铁湖泊充分研究微生物铁循环。这种光生铁氧化作用可能占化跃层中初级生产总量的10%。铁的氧化物不能被检测到，并推测立即减少铁还原微生物。推定的铁氧化剂和还原剂的序列从原位16 S rRNA基因扩增子文库中检索，并在我们的富集培养物中鉴定了其中的一些细菌，并补充了Fe（II）和FeS。基于我们的研究结果，我们提出了一个模型，其中铁被氧化的光养铁菌和微需氧菌，和铁氧化物立即减少异养铁还原剂，导致在一个隐藏的铁循环。我们推测，微生物铁循环可能是更普遍的水柱氧化还原，特别是那些在透光区，比以前认为的。
Iron redox reactions play an important role in carbon remineralization, supporting large microbial communities in iron-rich terrestrial and aquatic sediments. Stratified water columns with comparably low iron concentrations are globally widespread, but microbial iron cycling in these systems has largely been ignored. We found evidence for unexpectedly high iron turnover rates in the low (1-2 mu mol.l(-1)) iron waters of Lake Cadagno. Light-dependent, biological iron oxidation rates (1.4-13.8 mu mol.l(-1).d(-1)) were even higher than in ferruginous lakes with well-studied microbial iron cycles. This photoferrotrophic iron oxidation may account for up to 10% of total primary production in the chemocline. Iron oxides could not be detected and were presumably reduced immediately by iron-reducing microorganisms. Sequences of putative iron oxidizers and reducers were retrieved from in situ 16S rRNA gene amplicon libraries and some of these bacteria were identified in our enrichment cultures supplemented with Fe(II) and FeS. Based on our results, we propose a model in which iron is oxidized by photoferrotrophs and microaerophiles, and iron oxides are immediately reduced by heterotrophic iron reducers, resulting in a cryptic iron cycle. We hypothesize that microbial iron cycling may be more prevalent in water column redoxclines, especially those within the photic zone, than previously believed.