Testing the generation of fungal spore aerosols with a new atomization setup

To study bioaerosols under controlled conditions, aerosol chambers equipped with aerosol generators have been used for a long time. However, the method used for generation can change the constitution and properties of the bioaerosol produced, including the biological integrity of fungal spores, bacteria or airborne viruses. The properties of a bioaerosol in turn influence the results of detection, enumeration and identification methods downstream (Pogner et al., 2024). Recent developments of automatic bioaerosol monitors equipped with AI-based identification algorithms require simple and reliable generation of bioaerosols in the laboratory to collect  data for the machine learning trainings.

Figure 1 View into the SAG chamber through the window at the front, containing a petri dish with a fungal colony.

The Swisens Aerosol Generator (SAG) is an atomizer for efficient and gentle aerosolization of fungal spores, as well as other dry biological materials, for measurement with the SwisensPoleno and other instruments. The SAG principle is based on the design described by Lee et al. (2010), with improvements for better controllability and a higher yield. It consists of a chamber, shown in Figure 2, in which the petri dishes and other materials are placed. Pressured air, generated by a separate air supply unit, is led to a nozzle inside the chamber and directed over the biological materials. The horizontal air stream detaches the fungal spores into the air of the chamber, which can then be taken in by the instrument to measure the content.

 

Figure 2 Left: Aerosol chamber with HEPA filter at the top for clean air supply. Right: Air supply unit with digital flow meter, flow controls and air filter.

The structure and quantity of aerosolized particles is highly dependent on the fungi species, its growth stage and success, as well as the airflow onto the petri dish. Measurements with Cladosporium cladosporioides (Tested by Pogner et al. (2024) with SAG prototype) created, for example, numerous data of agglomerated spores and mycelium parts besides single spores, whereas Alternaria alternata constantly generated single spores in high numbers. With the SAG the process and the efficiency of fungal spores aerosolization can be improved, making it a new tool besides other fungal spore aerosols generation methods. This opens more opportunities to choose the best means of aerosolization depending on the fungal species and required particles.

 

References:

Lee, Jun Hyun, Gi Byung Hwang, Jae Hee Jung, Dae Hee Lee, und Byung Uk Lee. 2010. «Generation characteristics of fungal spore and fragment bioaerosols by airflow control over fungal cultures». Journal of Aerosol Science 41 (3): 319–25. https://doi.org/10.1016/j.jaerosci.2009.11.002.

Pogner, Clara-E, Elias Graf, Erny Niederberger, und Markus Gorfer. 2024. «What do spore particles look like - use of real-time measurements and holography imaging to view spore particles from four bioaerosol generators». Aerosol Science and Technology 58 (7): 1–17. https://doi.org/10.1080/02786826.2024.2338544.