Collaborative LExEn Research on the Role of Exopolymers in Arctic Sea Ice: Habitat Alteration and Microbial Cryoprotection

胞外聚合物（EPS）是由水生微生物分泌的粘液状物质，在海洋生态系统中起着重要作用。 拟议的研究将调查外聚合物物质改变海冰栖息地微观结构的潜力，并作为居住在冰结构内的微生物的冷冻保护剂。 主要研究目标如下：（1）确定海冰中存在的EPS池如何以及在多大程度上可能导致微生境的改变;（2）评估EPS作为低温保护的潜在作用;以及（3）确定EPS的主要海冰生产者沿着大量和特定外聚合物生产的相关环境线索。 这些目标将通过实验室和实地研究相结合来实现，包括基于文化和露天的冰生长。还将研究聚合物在冰脱盐过程中的作用（通过其对盐水粘度和冰渗透性的影响）以及在极低温度下防止孔隙闭合的作用。 这些研究结果将被比较，在准自然条件下的细菌和硅藻群落的原位EPS生产。 EPS的防冻效果及其与高浓度冬季盐水的关系将直接在阿拉斯加巴罗附近的北极冰盖进行原位实验。 拟议的工作不仅与低温生存策略及其对物理环境的影响有关，而且还与极地海洋生态和碳循环，极地冰盖的辐射和其他传输特性，低温生物学的工业应用以及木星卫星的潜在可居住性有关。

Exopolymeric substances (EPS), secreted in the form of mucous slime by aquatic microorganisms, are known to play important roles in marine ecosystems. The proposed research will investigate the potential for exopolymeric substances to alter the microstructure of the sea-ice habitat and to serve as cryoprotectants for microorganisms dwelling within ice structures. Main research goals are as follows: (1) to determine how and to what extent the pool of EPS present in sea ice may result in an alteration of the microhabitat; (2) to assess the potential role of EPS as cryoprotection; and (3) to determine the major sea-ice producers of EPS along with relevant environmental cues for bulk and specific exopolymer production. These objectives will be pursued through a combination of laboratory and field studies, including culture-based and open-air ice-growth. The role of polymers in ice desalination processes (through their effects on brine viscosity and ice permeability) and in preventing pore closure at very low temperatures will also be investigated. These findings will be compared to in-situ EPS production by bacterial and diatom communities under quasi-natural conditions. The cryoprotectant effects of EPS and their associations with highly concentrated wintertime brines will be examined directly with in-situ experimentation in the Arctic ice sheet near Barrow, Alaska. The proposed work is relevant not only to low-temperature survival strategies and their impact on the physical environment, but also in the general context of polar marine ecology and carbon cycling, radiative and other transfer properties of the polar ice cap, industrial applications in cryobiology, and the potential habitability of Jovian moons.