Eufemio Rosemary J, de Almeida Ribeiro Ingrid, Sformo Todd L, Laursen Gary A, Molinero Valeria, Fröhlich-Nowoisky Janine, Bonn Mischa, Meister Konrad
Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA.
Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA.
Biogeosciences. 2023;20(13):2805-2812. doi: 10.5194/bg-20-2805-2023. Epub 2023 Jul 14.
Forty years ago, lichens were identified as extraordinary biological ice nucleators (INs) that enable ice formation at temperatures close to 0°C. By employing INs, lichens thrive in freezing environments that surpass the physiological limits of other vegetation, thus making them the majority of vegetative biomass in northern ecosystems. Aerosolized lichen INs might further impact cloud glaciation and have the potential to alter atmospheric processes in a warming Arctic. Despite the ecological importance and formidable ice nucleation activities, the abundance, diversity, sources, and role of ice nucleation in lichens remain poorly understood. Here, we investigate the ice nucleation capabilities of lichens collected from various ecosystems across Alaska. We find ice-nucleating activity in lichen to be widespread, particularly in the coastal rainforest of Southeast Alaska. Across 29 investigated lichen, all species show ice nucleation temperatures above -15 °C and ~30% initiate freezing at temperatures above -6 °C. Concentration series of lichen ice nucleation assays in combination with statistical analysis reveal that the lichens contain two subpopulations of INs, similar to previous observations in bacteria. However, unlike the bacterial INs, the lichen INs appear as independent subpopulations resistant to freeze-thaw cycles and against temperature treatment. The ubiquity and high stability of the lichen INs suggest that they can impact local atmospheric processes and that ice nucleation activity is an essential trait for their survival in cold environments.
四十年前，地衣被确认为非凡的生物冰核（INs），能够在接近0°C的温度下形成冰。通过利用冰核，地衣在超越其他植被生理极限的冰冻环境中茁壮成长，因此成为北方生态系统中大部分的植物生物量。气溶胶化的地衣冰核可能进一步影响云的冰川形成，并有可能改变变暖北极地区的大气过程。尽管地衣具有生态重要性和强大的冰核活性，但其冰核的丰度、多样性、来源和作用仍知之甚少。在这里，我们研究了从阿拉斯加各地生态系统收集的地衣的冰核能力。我们发现地衣中的冰核活性很普遍，特别是在阿拉斯加东南部的沿海雨林中。在29种地衣中，所有物种的冰核温度都高于-15°C，约30%的物种在高于-6°C的温度下开始结冰。地衣冰核试验的浓度系列与统计分析表明，地衣含有两个冰核亚群，这与之前在细菌中的观察结果相似。然而，与细菌冰核不同的是，地衣冰核表现为独立的亚群，对冻融循环和温度处理具有抗性。地衣冰核的普遍性和高稳定性表明它们可以影响当地的大气过程，并且冰核活性是它们在寒冷环境中生存的基本特征。
