Effects of atmospheric conditions on ice nucleation activity of Pseudomonas
Effects of atmospheric conditions on ice nucleation activity of Pseudomonas
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DOI：
10.5194/acp-12-10667-2012
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发表时间：
2012-01-01
影响因子：
6.3
通讯作者：
Morris, C. E.
中科院分区：
文献类型：
--
作者：
Attard, E.;Yang, H.;Morris, C. E.
虽然已知来自细菌的冰核在已知的最高温度下对冰催化剂有效，但仍然需要定量数据来评估它们在云过程中的作用。本研究研究了三种典型的云层条件(i)酸性pH (ii) NO2和O-3暴露和（iii） UV-A暴露对四种假单胞菌冰核活性（INA）的影响。从云水中分离到3株丁香假单胞菌，从层球分离到CGina-01株荧光假单胞菌。在三种测试条件中，酸性pH对INA的影响最为显著，可能是由于冰核蛋白复合物的变性。暴露于NO2和O-3气体对两株丁香假单胞菌的INA无显著或微弱影响，而对荧光假单胞菌CGina-01的INA有显著影响。3株紫丁香假单胞菌的INA对NO2和o3暴露表现出不同的反应。不同假单胞菌的INA差异表明，对大气条件的反应可能是菌株特异性的。在UV-A照射后，观察到所有四种菌株的生存能力都大幅下降，而它们的INA仅略有下降。这证实了在某些条件下死亡的细菌细胞可以维持其INA的观点。总体而言，三种环境因子对INA的负面影响在温度升高时更为显著。我们的研究结果表明，在温度接近0℃的云中，细菌冰核在降水过程中的重要性可能会因一些环境因素而降低。
Although ice nuclei from bacterial origin are known to be efficient at the highest temperatures known for ice catalysts, quantitative data are still needed to assess their role in cloud processes. Here we studied the effects of three typical cloud conditions (i) acidic pH (ii) NO2 and O-3 exposure and (iii) UV-A exposure on the ice nucleation activity (INA) of four Pseudomonas strains. Three of the Pseudomonas syringae strains were isolated from cloud water and the phyllosphere and Pseudomonas fluorescens strain CGina-01 was isolated from Antarctic glacier ice melt. Among the three conditions tested, acidic pH caused the most significant effects on INA likely due to denaturation of the ice nucleation protein complex. Exposure to NO2 and O-3 gases had no significant or only weak effects on the INA of two P. syringae strains whereas the INA of P. fluorescens CGina-01 was significantly affected. The INA of the third P. syringae strain showed variable responses to NO2 and O-3 exposure. These differences in the INA of different Pseudomonas suggest that the response to atmospheric conditions could be strain-specific. After UV-A exposure, a substantial loss of viability of all four strains was observed whereas their INA decreased only slightly. This corroborates the notion that under certain conditions dead bacterial cells can maintain their INA. Overall, the negative effects of the three environmental factors on INA were more significant at the warmer temperatures. Our results suggest that in clouds where temperatures are near 0 degrees C, the importance of bacterial ice nucleation in precipitation processes could be reduced by some environmental factors.