Octanol-water distribution coefficients of fungal particles collected from the atmosphere

Abstract

Fungi are well-known spore-producing organisms that secrete particles of various shapes, sizes, surface properties, and other features to adapt to different environments. The released fungal particles, including spores, hyphae, and fragments, can act as ice nuclei and/or cloud condensation nuclei and actively participate in local and global hydrological cycles. The degree of hydrophobicity of fungal particle surfaces might play an important role in their ability to act as the ice nuclei or cloud condensation nuclei. Therefore, in this study, we employ the octanol–water distribution coefficient to identify the degree of hydrophobicity of the fungal particles collected from the atmosphere in Seoul, South Korea. The airborne fungal particles were collected from the atmosphere using a two-stage cyclone sampler. The collected fungal particles were classified based on their surface properties using the frozen water phase method. The taxon-specific octanol–water distribution coefficients of the fungal particles were determined by quantifying every taxon in each phase using the combination of quantitative PCR and high-throughput sequencing methods. The octanol–water distribution coefficients of Ascomycota and Basidiomycota, which are considered as the predominant phyla of fungi, were not statistically different across the sampling period. Additionally, the octanol–water distribution coefficients of the two phyla showed similar patterns of variation, which had been affected by sampling period. Moreover, the octanol–water distribution coefficients at genus rank showed a high variability across the sampling period. Hierarchical cluster analysis revealed that the fungal genera were not taxonomically grouped by the octanol–water distribution coefficients of each fungal genus. Spearmans correlation analysis and generalized linear model demonstrated the potential possibility that some environmental factors, climatological condition, and concentration of anthropogenic air pollutants measured weekly could modify the fungal particle surface and change the degree of octanol–water distribution coefficients. The result of this study revealed that the degree of hydrophobicity of fungal particles could vary according to species. In addition, the degree of hydrophobicity of fungal particles might be affected by the ambient air pollutants, which is likely influenced by the concentration of air pollutants and the residence time of fungal particles in the atmosphere. Consequently, we expect that ice nucleation and cloud condensation nucleation activity of fungal particles could vary depending on the fungal species and residence time of fungal particles in the atmosphere.