Spores of many common airborne fungi reveal no ice nucleation activity in oil immersion freezing experiments

Pummer, Bernhard; Atanasova, Lea; Bauer, Heidi; Bernardi, Johannes; Druzhinina, Irina S.; Fröhlich-Nowoisky, Janine; Grothe, Hinrich

doi:10.5194/bg-10-8083-2013

Cited by 14 publications

(22 citation statements)

References 36 publications

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“…It is possible that submicron contributions to this particle type are however being under-sampled by WIBS. The evidence for ice nucleating efficacy of fungal spores is conflicting (Pummer et al, 2013;Morris et al, 2013;Haga et al, 2013;. No diurnal trend in IN concentration was reported and the concentrations of cluster B 3 during rain events were less than the maximum observed IN concentrations, suggesting that they were not significantly ice active based on the measured IN total concentrations at this location.…”

Section: Discussionmentioning

confidence: 83%

“…Certain PBAs have been shown to act as highly efficient ice nuclei (IN) at relatively warm temperatures (e.g. Diehl et al, 2001Diehl et al, , 2002Haga et al, 2013;Möhler et al, 2008a;Morris et al, 2004Morris et al, , 2013Pummer et al, 2013). However, based on the limited, currently available observations, bioaerosol concentrations are generally considered to be negligible contributors to ice formation processes at temperatures below −30 • C (Cziczo et al, 2013).…”

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confidence: 99%

“…Pummer et al (2013) recently reported that common fungal spore species do not exhibit significantly ice activity and so they suggested that the contribution of fungal spores to observed IN concentration is negligible. In contrast, other groups have reported fungal species with very efficient ice nucleating behaviour at high temperatures (e.g.…”

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confidence: 99%

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Characterisation of bioaerosol emissions from a Colorado pine forest: results from the BEACHON-RoMBAS experiment

et al. 2014

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Abstract. The behaviour of primary biological aerosols (PBAs) at an elevated, un-polluted North American forest site was studied using an ultra violet-light induced fluorescence (UV-LIF) measurement technique in conjunction with hierarchical agglomerative cluster analysis (HA-CA). Contemporaneous UV-LIF measurements were made with two wide-band integrated bioaerosol spectrometers, WIBS-3 and WIBS-4, which sampled close to the forest floor and via a continuous vertical profiling system, respectively. Additionally, meteorological parameters were recorded at various heights throughout the forest and used to estimate PBAP (Primary Biological Aerosol Particle) fluxes. HA-CA using data from the two, physically separated WIBS instruments independently yielded very similar cluster solutions.All fluorescent clusters displayed a diurnal minimum at midday at the forest floor with maximum concentration occurring at night. Additionally, the number concentration of each fluorescent cluster was enhanced, to different degrees, during wet periods. A cluster that displayed the greatest enhancement and highest concentration during sustained wet periods appears consistent with behaviour reported for fungal spores. A cluster that appears to be behaviourally consistent with bacteria dominated during dry periods. Fluorescent particle concentrations were found to be greater within the forest canopy than at the forest floor, indicating that the canopy was the main source of these particles rather than the minimal surface vegetation, which appeared to contribute little to overall PBA concentrations at this site.Fluorescent particle concentration was positively correlated with relative humidity (RH), and parameterisations of the aerosol response during dry and wet periods are reported. The aforementioned fungal spore-like cluster displayed a strong positive response to increasing RH. The bacteria-like cluster responded more strongly to direct rain-fall events than other PBA types. Peak concentrations of this cluster are shown to be linearly correlated to the log of peak rainfall rates.Parallel studies by and Prenni et al. (2013) showed that the fluorescent particle concentrations correlated linearly with ice nuclei (IN) concentrations at this site during rain events. We discuss this result in conjunction with our cluster analysis to appraise the candidate IN.

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Section: Discussionmentioning

confidence: 83%

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confidence: 99%

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Characterisation of bioaerosol emissions from a Colorado pine forest: results from the BEACHON-RoMBAS experiment

et al. 2014

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“…-they are unlikely to be chitin and related fungal cell wall polysaccharides since Pummer et al (2013) found no appreciable ice nucleation activity above −26 • C in fungal spores from a range of common fungi (other than in a known IN Fusarium);…”

Section: Discussionmentioning

confidence: 96%

Sources of organic ice nucleating particles in soils

et al. 2016

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Abstract. Soil organic matter (SOM) may be a significant source of atmospheric ice nucleating particles (INPs), especially of those active > −15 • C. However, due to both a lack of investigations and the complexity of the SOM itself, the identities of these INPs remain unknown. To more comprehensively characterize organic INPs we tested locally representative soils in Wyoming and Colorado for total organic By contrast, lysozyme, which digests bacterial cell walls, only reduced INPs active at ≥ −7.5 or ≥ −6 • C, depending on the soil. The known IN bacteria were not detected in any soil, using PCR for the ina gene that codes for the active protein. We directly isolated and photographed two INPs from soil, using repeated cycles of freeze testing and subdivision of droplets of dilute soil suspensions; they were complex and apparently organic entities. Ice nucleation activity was not affected by digestion of Proteinase K-susceptible proteins or the removal of entities composed of fulvic and humic acids, sterols, or aliphatic alcohol monolayers. Organic INPs active colder than −10 to −12 • C were resistant to all investigations other than heat, oxidation with H 2 O 2 , and, for some, digestion with papain. They may originate from decomposing plant material, microbial biomass, and/or the humin component of the SOM. In the case of the latter then they are most likely to be a carbohydrate. Reflecting the diversity of the SOM itself, soil INPs have a range of sources which occur with differing relative abundances.

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“…This might be caused by the adhesion of the organic matter in the extracts to the column packing, which undermines the separation principle. The tendency for adhesion of organic matter from pollen was investigated by Pummer et al (2013b). Nevertheless, there was an unambiguous maximum in the 335 to 860 kDa fraction before and after digestion.…”

Section: Experimental Characterization Of Inmsmentioning

confidence: 99%

Ice nucleation by water-soluble macromolecules

et al. 2015

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Cloud glaciation is critically important for the global radiation budget (albedo) and for initiation of precipitation. But the freezing of pure water droplets requires cooling to temperatures as low as 235 K. Freezing at higher temperatures requires the presence of an ice nucleator, which serves as a template for arranging water molecules in an ice-like manner. It is often assumed that these ice nucleators have to be insoluble particles. We point out that also free macromolecules which are dissolved in water can efficiently induce ice nucleation: the size of such ice nucleating macromolecules (INMs) is in the range of nanometers, corresponding to the size of the critical ice embryo. As the latter is temperature-dependent, we see a correlation between the size of INMs and the ice nucleation temperature as predicted by classical nucleation theory. Different types of INMs have been found in a wide range of biological species and comprise a variety of chemical structures including proteins, saccharides, and lipids. Our investigation of the fungal species Acremonium implicatum, Isaria farinosa, and Mortierella alpina shows that their ice nucleation activity is caused by proteinaceous water-soluble INMs. We combine these new results and literature data on INMs from fungi, bacteria, and pollen with theoretical calculations to develop a chemical in-terpretation of ice nucleation and water-soluble INMs. This has atmospheric implications since many of these INMs can be released by fragmentation of the carrier cell and subsequently may be distributed independently. Up to now, this process has not been accounted for in atmospheric models

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Spores of many common airborne fungi reveal no ice nucleation activity in oil immersion freezing experiments

Cited by 14 publications

References 36 publications

Characterisation of bioaerosol emissions from a Colorado pine forest: results from the BEACHON-RoMBAS experiment

Characterisation of bioaerosol emissions from a Colorado pine forest: results from the BEACHON-RoMBAS experiment

Sources of organic ice nucleating particles in soils

Ice nucleation by water-soluble macromolecules

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