School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
Arch Microbiol. 2010 Dec;192(12):1031-8. doi: 10.1007/s00203-010-0634-0. Epub 2010 Oct 9.
Cyanobacteria are able to survive in various extreme environments via the production of organic compounds known as compatible solutes. In particular, cyanobacteria are capable of inhabiting hypersaline environments such as those found in intertidal regions. Cyanobacteria in these environments must possess regulatory mechanisms for surviving the changing osmotic pressure as a result of desiccation, rainfall and tidal fluxes. The objective of this study was to determine the compatible solutes that are accumulated by cyanobacteria from hypersaline regions, and specifically, the stromatolite ecosystems of Shark Bay, Western Australia. Previously, the cyanobacterial populations associated with these stromatolites were characterized in two separate studies. Compatible solutes were extracted from isolated cyanobacteria here and identified by nuclear magnetic resonance. As the media of isolation contained no complex carbon source, the solutes accumulated were likely synthesized by the cyanobacteria. The data indicate that from this one habitat taxonomically distinct cyanobacteria exposed to varying salinities accumulate a range of known compatible solutes. In addition, taxonomically similar cyanobacteria do not necessarily accumulate the same compatible solutes. Glucosylglycerol, a compatible solute unique to marine cyanobacteria was not detected; however, various saccharides, glycine betaine, and trimethylamine-N-oxide were identified as the predominant solutes. We conclude that the cyanobacterial communities from these hypersaline stromatolites are likely to possess more complex mechanisms of adaptation to osmotic stress than previously thought. The characterization of osmoregulatory properties of stromatolite microorganisms provides further insight into how life can thrive in such extreme environments.
蓝藻能够通过产生被称为相容性溶质的有机化合物在各种极端环境中生存。特别是，蓝藻能够栖息在高盐环境中，例如潮间带地区。这些环境中的蓝藻必须具有调节机制，以应对由于干燥、降雨和潮汐流动导致的渗透压变化而生存。本研究的目的是确定来自高盐环境的蓝藻积累的相容性溶质，特别是澳大利亚西部鲨鱼湾的叠层石生态系统。以前，在两项独立的研究中对与这些叠层石相关的蓝藻种群进行了特征描述。在这里，从分离的蓝藻中提取相容性溶质，并通过核磁共振进行鉴定。由于分离的培养基中没有复杂的碳源，因此积累的溶质可能是由蓝藻合成的。数据表明，来自这一单一栖息地的分类上不同的蓝藻暴露在不同的盐度下会积累一系列已知的相容性溶质。此外，分类上相似的蓝藻不一定积累相同的相容性溶质。未检测到海洋蓝藻特有的相容性溶质葡萄糖甘油，但鉴定出各种糖、甘氨酸甜菜碱和三甲胺 N-氧化物为主要溶质。我们得出结论，来自这些高盐叠层石的蓝藻群落可能具有比以前认为的更复杂的渗透压应激适应机制。对叠层石微生物渗透调节特性的表征进一步深入了解了生命如何在如此极端的环境中茁壮成长。
