Dissolved extracellular polymeric substances (dEPS) dynamics and bacterial growth during sea ice formation in an ice tank study
Dissolved extracellular polymeric substances (dEPS) dynamics and bacterial growth during sea ice formation in an ice tank study
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DOI：
10.1007/s00300-011-1112-0
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发表时间：
2012-05-01
期刊：
影响因子：
1.7
通讯作者：
Thomas, David N.
中科院分区：
文献类型：
--
作者：
Aslam, Shazia N.;Underwood, Graham J. C.;Thomas, David N.
众所周知，细胞外聚合物（EPS）可以帮助微生物在海冰的极端条件下生存。据报道，两极的海冰中存在高浓度的EPS；然而，迄今为止，对海冰形成过程中EPS的产生和动态研究甚少。本研究追踪了冰形成初期现有和新形成的溶解有机物（DOM）的产生和分配，包括溶解碳水化合物（dCHO）、溶解脲酸（dUA）和溶解EPS (dEPS)，以及细菌丰度。在6天的重复中生态环境实验中，用北海海水(A)外加DOM （NSW）和(B)外加藻源DOM （ADOM）形成海冰。在ADOM海水中，细菌总数（TBN）在整个实验过程中都在增加，而在NSW海水中，细菌仅在5d内生长。在发展中的海冰中，TBN逐渐减少，但新南威尔士州的下降幅度是ADOM冰面的2倍。冰中dCHO的浓度显著增加。在ADOM冰的最冷部分，dEPS的百分比贡献最高（63%），表明发展了一个适应冷的群落，产生dEPS可能是为了低温保护和/或保护免受高盐度盐水的侵害。我们认为，在冰形成的早期，来自母海水的外来有机物被吸收到海冰中，一旦冰形成，溶解有机碳库的浓度和组成就会发生显著变化，这主要是由细菌产生的本地DOM引起的。
Extracellular polymeric substances (EPS) are known to help microorganisms to survive under extreme conditions in sea ice. High concentrations of EPS are reported in sea ice from both poles; however, production and dynamics of EPS during sea ice formation have been little studied to date. This investigation followed the production and partitioning of existing and newly formed dissolved organic matter (DOM) including dissolved carbohydrates (dCHO), dissolved uronic acids (dUA) and dissolved EPS (dEPS), along with bacterial abundances during early stages of ice formation. Sea ice was formed from North Sea water with (A) ambient DOM (NSW) and (B) with additional algal-derived DOM (ADOM) in a 6d experiment in replicated mesocosms. In ADOM seawater, total bacterial numbers (TBN) increased throughout the experiment, whereas bacterial growth occurred for 5d only in the NSW seawater. TBN progressively decreased within developing sea ice but with a 2-fold greater decline in NSW compared to ADOM ice. There were significant increases in the concentrations of dCHO in ice. Percentage contribution of dEPS was highest (63%) in the colder, uppermost parts in ADOM ice suggesting the development of a cold-adapted community, producing dEPS possibly for cryo-protection and/or protection from high salinity brines. We conclude that in the early stages of ice formation, allochthonous organic matter was incorporated from parent seawater into sea ice and that once ice formation had established, there were significant changes in the concentrations and composition of dissolved organic carbon pool, resulting mainly from the production of autochthonous DOM by the bacteria.