Data from: Cultivable, halotolerant ice nucleating bacteria and fungi in coastal precipitation. In Center for Aerosol Impacts on Chemistry of the Environment (CAICE)

Publication abstract: Ice nucleating particles (INPs) are a rare subset of aerosol particles that initiate cloud droplet freezing at temperatures above the homogenous freezing point of water (-38 °C). Considering that the ocean covers 70% of the earth’s surface and represent a large potential source of INPs, it is imperative that the uncertainties in the identities and emissions of ocean INP become better understood. However, the specific underlying drivers of marine INP emissions and their identities remain largely unknown due to limited observations and the challenge involved in isolating exceptionally rare IN forming particles. By generating nascent sea spray aerosol (SSA) over a range of biological conditions, mesocosm studies show that microbes can contribute to marine INPs. Here, we identify 14 (30%) cultivable halotolerant ice nucleating microbes and fungi among 47 total isolates recovered from precipitation and aerosol samples collected in coastal air in Southern California. IN isolates collected in coastal air were found to nucleate ice from extremely warm to moderate freezing temperatures (-2.3 to -18 °C). Air mass trajectory analyses, and cultivability in marine growth media indicate marine origins of these isolates. Further phylogenetic analysis confirmed that at least two of the 14 IN isolates were of marine origin. Moreover, results from cell washing experiments demonstrate that most IN isolates maintained freezing activity in the absence of nutrients and cell growth media. This study provides confirmation of previous studies’ findings that implicated microbes as a potential source of marine INPs and additionally demonstrates links between precipitation, marine aerosol and IN microbes.论文摘要：冰核粒子（Ice nucleating particles，INPs）是气溶胶粒子中的稀有子类，可在高于水的均质冻结温度（-38℃）的条件下触发云滴冻结。鉴于海洋覆盖地球70%的表面积，且是冰核粒子的重要潜在来源，因此亟需加深对海洋冰核粒子的属性与排放过程中存在的不确定性的认识。然而，由于观测数据有限，且分离极为稀有的成冰粒子存在技术难题，海洋冰核粒子排放的具体潜在驱动因素及其属性仍未得到充分探明。通过在一系列生物条件下生成新生海喷雾气溶胶（sea spray aerosol，SSA），中宇宙实验研究表明微生物可对海洋冰核粒子产生贡献。本研究从南加州沿海空气采集的降水与气溶胶样品中分离得到共计47株菌株，其中14株（占比30%）为可培养的耐盐冰核微生物与真菌。研究发现，从沿海空气中采集的冰核菌株可在极暖至中等冻结温度（-2.3℃至-18℃）范围内实现成冰。气团轨迹分析以及在海洋生长培养基中的可培养性结果表明，这些菌株源自海洋。进一步的系统发育分析证实，14株冰核菌株中至少有2株确实为海洋起源。此外，细胞洗涤实验的结果表明，多数冰核菌株在缺乏营养物质与细胞培养基的条件下仍能保持成冰活性。本研究不仅证实了此前研究将微生物视为海洋冰核粒子潜在来源的结论，还进一步揭示了降水、海洋气溶胶与冰核微生物之间的关联。