Taxonomy and Biogeography of Polar Sea Ice Bacteria

在冬季，温度变得足够低，海水在高纬度的极地地区结冰。海面上的冰层可能增厚到两码多深。随着来年春天的临近，微生物开始在海冰底部生长。这个海冰微生物群落以海冰藻类为主，它们生长到足够的密度，使下层呈现红色到棕色。细菌从冰藻中获取营养，并与它们一起在冰层中生长。尽管对海冰藻类进行了大量的研究，但对在这种寒冷环境中生长的细菌种类知之甚少。华盛顿大学（University of Washington）的詹姆斯·斯特利（James Staley）博士从南极和北极地区收集了海冰细菌，并发现了一些新的形式，其中一些在细胞中有专门的气体液泡。利用标准的细菌学测试和较新的DNA分析分子方法，包括核糖体基因测序，斯特利博士正在描述从极地海冰收集的各种细菌菌株的特征。其中一个目标是确定在南极和北极冰群落中是否存在相同种类的细菌。另一个目的是分析在两个地理上不同的地区存在的分类多样性的范围。关于真正适应寒冷的细菌的知识将最终对极地和寒冷海水中的分解和废物处理产生影响。

During the winter the temperature becomes sufficiently low for sea water to freeze in high latitude polar regions. The layer of ice on the sea may thicken to over two yards in depth. As the following spring approaches, microorganisms begin growing in the lower foot of the sea ice. This community of sea ice microorganisms is dominated by sea ice algae that grow to sufficient density to impart a red to brown color to the lower layer. Bacteria derive nutrients from the ice algae and grow with them in the layer. Although considerable work has been performed on the sea ice algae, little is yet known about the kinds of bacteria that grow in this cold environment. Dr. James Staley of the University of Washington has collected sea ice bacteria from both antarctic and arctic zones and has discovered novel forms, some with specialized gas vacuoles in their cells. Using standard bacteriological tests as well as newer molecular methods of DNA analysis, including ribosomal gene sequencing, Dr. Staley is characterizing the various bacterial strains collected from polar sea ice. One objective is to determine whether the same species of bacteria occur in both the north and south polar ice communities. Another objective is to assay the range of taxonomic diversity present in the two geographically separate regions. Knowledge about true cold-adapted bacteria would have eventual implications for decomposition and waste disposal in polar regions and cold marine waters.