What do spore particles look like - use of real-time measurements and holography imaging to view spore particles from four bioaerosol generators

Abstract

To study bioaerosols under controlled conditions, aerosol chambers equipped with aerosol generators have been used for a long time. The method used for generation can change the constitutionand properties of the bioaerosol produced, including the viability of fungal spores, bacteria or airborne viruses. The properties of a bioaerosol in turn influence the results of detection and enumeration methods downstream. To evaluate and compare bioaerosol generators, previous methods provided either real-time data without particle characterization, relied on labor-intensive microscopy or used culturing, which has high variability. In our study, we used the novel instrument SwisensPoleno Jupiter, providing real-time enumeration and subsequent bioaerosols characterization through holographic image analysis. With this tool, we investigated the characteristics of bioaerosols produced by four different aerosol generators using fungal spores from Aspergillus brasiliensis, Cladosporium cladosporioides and Trichoderma longibrachiatum in controlled chamber environments. The rotating brush generator (RBG) produce small, round particles for A. brasiliensis, between 5 and 15 µm, while the fungal aerosol generator (FAG) released small particles for C. cladosporioides and T. longibrachiatum. Conversely, the SwisensAtomizer (SWA) produced larger non-spheric particles, likely spore aggregates, and the liquid sparging aerosolizer (LSA), exhibited a high portion of datapoints with empty images, supposedly water droplets. All generators showed a wide range of particle sizes. Holographic image analysis revealed that the choice of bioaerosol generator had a significant influence on the constitutionof produced aerosols, in terms of proportions of single spores, chains and agglomerates, emphasizing the importance to select the bioaerosol generator depending on the desired aerosol.

Copyright © 2024 American Association for Aerosol Research

Graphical Abstract

Editor:

• Hans Moosmüller

Acknowledgments

Thanks to the laboratory team of AIT for help in producing the fungal spore dust, especially Lena Piglmann and Marija Gumze. Special thanks to Christian Amsüss for support and reviewing work.

Disclosure statement

The present scientific study was carried out in collaboration with the company SWISENS AG within the framework of research cooperation. SWISENS AG is a company that specializes in the development of solutions for aerosol particle measurement. The employees of the company, Mr. Erny Niederberger (position: Managing Director) and Mr. Elias Graf (position: Application Engineer), actively participated in the study. Mr. Erny Niederberger assisted in the design of the study and Mr. Elias Graf assisted in the data analysis. It should be noted that there are potential conflicts of interest as SWISENS AG develops and distributes the SwisensPoleno Jupiter measurement instruments, which is related to the topic of the study. However, Swisens AG considers the independence of the researchers to be essential and has not taken any influence to embellish any results.

Additional information

Funding

This work was co-funded by Innosuisse and MeteoSwiss. Swisens and AIT supported the study by providing labor contributions.