Macromolecular fungal ice nuclei in Fusarium: effects of physical and chemical processing
Macromolecular fungal ice nuclei in Fusarium: effects of physical and chemical processing
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DOI：
10.5194/bg-16-4647-2019
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发表时间：
2019-12-09
期刊：
影响因子：
4.9
通讯作者：
Froehlich-Nowoisky, Janine
中科院分区：
文献类型：
--
作者：
Kunert, Anna T.;Poehlker, Mira L.;Froehlich-Nowoisky, Janine
一些生物颗粒和大分子是特别有效的冰核（IN），在接近0摄氏度的温度下引发冰的形成。生物颗粒对云冰川作用和降水形成的影响仍然知之甚少，在对生命和气候的相互作用和共同进化的科学理解方面存在很大差距。真菌中的冰核活性首先在世界性的镰刀菌属中发现，镰刀菌广泛存在于土壤和植物中，已在大气气溶胶和云水样品中发现，可以被认为是研究得最好的冰核活性（IN活性）真菌。然而，镰刀菌内冰核活性的频率和分布仍然难以捉摸。在这里，我们测试了来自65种不同镰刀菌的100多个菌株的冰核活性。总体上，所有测试物种中的类似11%包括IN活性菌株，并且所有测试菌株中的类似16%显示高于-12 ° C的冰成核活性。除了已知具有冰核活性的镰刀菌外，F. armeniacum、杏F. beglion，F. concentricum和F. langsethiae是新发现的IN活性。对于所有测试的镰刀菌属物种，每克菌丝体的IN的累积数目与其他生物IN（如隐生帚霉、高山被孢霉和Snomax）相当。过滤实验表明，无细胞的冰成核大分子（INMs）从镰刀菌小于100 kDa，分子聚集体可以在溶液中形成。长期储存和冻融循环实验表明，真菌IN在水溶液中保持活性超过几个月，并在反复冻融的过程中。暴露于臭氧和二氧化氮在大气相关浓度水平也没有影响冰成核活动。然而，在40至98摄氏度的热处理强烈降低了所观察到的IN浓度，证实了早期的假设，即镰刀菌属中的INM主要由蛋白质化合物组成。频率和广泛分布的冰核活动的镰刀菌属内，结合大气相关条件下的IN的稳定性，建议真菌IN对地球的水循环和气候比以前假设的更大的影响。
Some biological particles and macromolecules are particularly efficient ice nuclei (IN), triggering ice formation at temperatures close to 0 degrees C. The impact of biological particles on cloud glaciation and the formation of precipitation is still poorly understood and constitutes a large gap in the scientific understanding of the interactions and coevolution of life and climate. Ice nucleation activity in fungi was first discovered in the cosmopolitan genus Fusarium, which is widespread in soil and plants, has been found in atmospheric aerosol and cloud water samples, and can be regarded as the best studied ice-nucleation-active (IN-active) fungus. The frequency and distribution of ice nucleation activity within Fusarium, however, remains elusive. Here, we tested more than 100 strains from 65 different Fusarium species for ice nucleation activity. In total, similar to 11% of all tested species included IN-active strains, and similar to 16% of all tested strains showed ice nucleation activity above -12 degrees C. Besides Fusarium species with known ice nucleation activity, F. armeniacum, F. begoniae, F. concentricum, and F. langsethiae were newly identified as IN-active. The cumulative number of IN per gram of mycelium for all tested Fusarium species was comparable to other biological IN like Sarocladium implicatum, Mortierella alpina, and Snomax (R). Filtration experiments indicate that cell-free ice-nucleating macromolecules (INMs) from Fusarium are smaller than 100 kDa and that molecular aggregates can be formed in solution. Long-term storage and freeze-thaw cycle experiments revealed that the fungal IN in aqueous solution remain active over several months and in the course of repeated freezing and thawing. Exposure to ozone and nitrogen dioxide at atmospherically relevant concentration levels also did not affect the ice nucleation activity. Heat treatments at 40 to 98 degrees C, however, strongly reduced the observed IN concentrations, confirming earlier hypotheses that the INM in Fusarium largely consists of a proteinaceous compound. The frequency and the wide distribution of ice nucleation activity within the genus Fusarium, combined with the stability of the IN under atmospherically relevant conditions, suggest a larger implication of fungal IN on Earth's water cycle and climate than previously assumed.