Tolerance of pennate diatoms (Bacillariophyceae) to experimental freezing: comparison of polar and temperate strains
Tolerance of pennate diatoms (Bacillariophyceae) to experimental freezing: comparison of polar and temperate strains
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DOI：
10.1080/00318884.2019.1591835
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发表时间：
2019-01-01
期刊：
影响因子：
1.6
通讯作者：
Sabbe, Koen
中科院分区：
文献类型：
--
作者：
Hejdukova, Eva;Pinseel, Eveline;Sabbe, Koen
尽管极地地区的特点是极端环境条件，整体气温较低，并且昼夜和季节温度波动往往明显，但硅藻（硅藻纲）在广泛的非海洋极地生境中繁衍生息，这表明它们很好地适应了这些恶劣的条件。在这项研究中，对来自淡水和陆地栖息地、属于不同形态种的 17 个极地和 9 个温带硅藻菌株的营养细胞和休眠细胞的冷冻耐受性进行了实验测试。大多数菌株是从南极洲海域（詹姆斯罗斯岛和维加岛）、北极高地（斯匹次卑尔根岛）和欧洲的地点新分离出来的。将培养物暴露于五种不同温度（-4、-20、-40和-180摄氏度）、冷冻速率（逐渐、突然）、时间（1小时、12小时）和解冻速率（慢、快）的冷冻处理。结果表明硅藻对实验冷冻敏感。冷冻温度对菌株存活有显着影响：所有菌株在-4℃下都能存活；大多数在-20°C 下幸存；其中有 5 个在 -40 ℃ 下幸存下来，其中 4 个（均属于 Pinnularia borealis 复合体）在液氮（-180 摄氏度）中冷冻后幸存下来。冷却和解冻速率对存活率有显着影响：突然冷却和缓慢解冻导致的存活率比逐渐冷却和快速解冻低得多。冷冻处理后，静息细胞比营养细胞表现出更好的生长，但仅限于 -4 摄氏度处理。令人惊讶的是，在极地和温带菌株之间没有观察到生长恢复的显着差异。
Although polar regions are characterised by extreme environment conditions with overall low temperatures and often pronounced diurnal to seasonal temperature fluctuations, diatoms (Bacillariophyceae) thrive in a wide range of nonmarine polar habitats, suggesting that they are well adapted to these harsh conditions. In this study, tolerance to freezing of vegetative and resting cells of 17 polar and nine temperate diatom strains, belonging to different morphospecies and originating from both freshwater and terrestrial habitats, was experimentally tested. Most strains were newly isolated from sites in Maritime Antarctica (James Ross Island and Vega Island), the High Arctic (Spitsbergen) and Europe. Cultures were exposed to five freezing treatments differing in temperature (-4, -20, -40 and -180 degrees C), freezing rate (gradual, abrupt), time (1 h, 12 h) and thawing rate (slow, fast). Results indicated that diatoms were sensitive to experimental freezing. Freezing temperatures had a significant effect on strain survival: all strains survived -4 degrees C; most survived -20 degrees C; five survived -40 and four of these (all belonging to the Pinnularia borealis complex) survived freezing in liquid nitrogen (-180 degrees C). The cooling and thawing rate had a significant impact on survival: abrupt cooling and slow thawing resulted in much lower survival rates than gradual cooling and fast thawing. Resting cells showed better growth than vegetative cells after freezing treatment but only in the -4 degrees C treatment. Surprisingly, no striking differences in growth recovery were observed between polar and temperate strains.