Transport of microbes in the atmosphere allows them to spread and to colonize new habitats. To survive the harsh environmental conditions encountered in the atmosphere, these microorganisms have to possess properties that allow them to resist atmospheric stress. We combined physiological experiments and genome analysis of Pseudomonas syringae strain R10.79, previously isolated from rain, to decipher the strain’s ability to withstand these challenges and identify the mechanisms behind the resistance. We used laboratory experiments to simulate different atmospheric stress factors and evaluated cell survival using fluorescent staining and flow cytometry. We found that while P. syringae R10.79 was resistant to oxidative, osmotic, UVB radiation-induced and freezing stress, it was sensitive to desiccation on surfaces. Strain R10.79 possesses a range of genes that would allow the strain to mitigate atmospheric stresses, such as cold shock and osmotic shock genes as well as genes encoding for properties that relate to UV irradiation resistance. Studying the substrate spectrum of strain R10.79, we uncovered that it can utilize carbon compounds abundant in the atmosphere including acetate, succinate and formate. In addition, strain R10.79 possesses metabolic pathways to utilize formaldehyde and methanol as sole carbon sources. These compounds could support the metabolic activity of strain R10.79 while suspended in the atmosphere during periods with sufficiently high relative humidity. Finally, we found that when growing on acetate, strain R10.79 produces several volatile organic compounds such as isoprene and methanol, for which we propose biochemical pathways and which are relevant for atmospheric chemistry and climate. The results reported in this study will support our general aim at establishing this strain as a model organism to study microbial responses to atmospheric conditions.

中文翻译：

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与从雨水中分离的冰核活性丁香假单胞菌菌株 R10.79 的大气扩散相关的特性

微生物在大气中的传播使它们能够传播并定居新的栖息地。为了在大气中遇到的恶劣环境条件下生存，这些微生物必须具有抵抗大气压力的特性。我们将之前从雨中分离出来的丁香假单胞菌菌株 R10.79 的生理实验和基因组分析相结合，以破译该菌株抵御这些挑战的能力并确定抗性背后的机制。我们使用实验室实验来模拟不同的大气压力因素，并使用荧光染色和流式细胞术评估细胞存活率。我们发现，虽然丁香假单胞菌 R10.79 对氧化、渗透、UVB 辐射诱导和冷冻应激具有抵抗力，但它对表面干燥敏感。应变 R10。79 拥有一系列基因，可以让该菌株减轻大气压力，例如冷休克和渗透休克基因以及编码与抗紫外线辐射相关的特性的基因。研究菌株 R10.79 的底物谱，我们发现它可以利用大气中丰富的碳化合物，包括乙酸盐、琥珀酸盐和甲酸盐。此外，菌株 R10.79 具有利用甲醛和甲醇作为唯一碳源的代谢途径。这些化合物可以支持菌株 R10.79 在相对湿度足够高的时期悬浮在大气中的代谢活动。最后，我们发现在醋酸盐上生长时，菌株 R10.79 会产生几种挥发性有机化合物，如异戊二烯和甲醇，为此，我们提出了与大气化学和气候相关的生化途径。本研究报告的结果将支持我们将这种菌株建立为模式生物以研究微生物对大气条件的反应的总体目标。