Crucial role of extracellular polysaccharides in desiccation and freezing tolerance in the terrestrial cyanobacterium Nostoc commune
Crucial role of extracellular polysaccharides in desiccation and freezing tolerance in the terrestrial cyanobacterium Nostoc commune
复制标题
DOI：
10.1128/aem.71.11.7327-7333.2005
复制
发表时间：
2005-11-01
影响因子：
4.4
通讯作者：
Sakamoto, T
中科院分区：
文献类型：
--
作者：
Tamaru, Y;Takani, Y;Sakamoto, T
蓝细菌地木耳适应陆地环境，具有世界性分布。本研究探讨了胞外多糖（EPS）在N.公社被检查。尽管在干燥的菌落中没有检测到光合O-2的进化，但细胞在再水化后迅速恢复了产生O-2的能力。空气干燥的菌落含有约10%（wt/wt）的水，并且具有EPS的现场隔离的天然菌落是高度吸水的，并且通过大气水分快速水合。发菜菌落中EPS包埋的细胞具有高度的耐干燥性，空气干燥不会破坏O-2的释放。虽然N. commune被确定为嗜温蓝藻，具有EPS的细胞在干燥状态下耐热。用搅拌器将菌落搅拌，用粗滤纸过滤，可将EPS从细胞中除去。这种去除EPS的处理并不损害念珠藻细胞或其释放O-2的能力，但O-2的释放被EPS耗尽的细胞的干燥处理显著损害。实验室培养菌株KU 002与EPS耗竭细胞相似，EPS含量少，对干燥高度敏感。在EPS耗竭的细胞中，O-2释放对冻融处理也很敏感。这些结果表明，N.在干旱和冻融过程中，公社对光合作用的胁迫耐受性至关重要。
The cyanobacterium Nostoc commune is adapted to the terrestrial environment and has a cosmopolitan distribution. In this study, the role of extracellular polysaccharides (EPS) in the desiccation tolerance of photosynthesis in N. commune was examined. Although photosynthetic O-2, evolution was not detected in desiccated colonies, the ability of the cells to evolve O-2 rapidly recovered after rehydration. The air-dried colonies contained approximately 10% (wt/wt) water, and field-isolated, natural colonies with EPS were highly water absorbent and were rapidly hydrated by atmospheric moisture. The cells embedded in EPS in Nostoc colonies were highly desiccation tolerant, and O-2 evolution was not damaged by air drying. Although N. commune was determined to be a mesophilic cyanobacterium, the cells with EPS were heat tolerant in a desiccated state. EPS could be removed from cells by homogenizing colonies with a blender and filtering with coarse filter paper. This treatment to remove EPS did not damage Nostoc cells or their ability to evolve O-2, but O-2 evolution was significantly damaged by desiccation treatment of the EPS-depleted cells. Similar to the EPS-depleted cells, the laboratory culture strain KU002 had only small amount of EPS and was highly sensitive to desiccation. In the EPS-depleted cells, O-2 evolution was also sensitive to freeze-thaw treatment. These results strongly suggest that EPS of N. commune is crucial for the stress tolerance of photosynthesis during desiccation and during freezing and thawing.