Potential Respiratory Deposition and Species Composition of Airborne Culturable, Viable, and Non-Viable Fungi during Occupancy in a Pig Farm

John White,Jeppe Nielsen,Anne Madsen

doi:10.3390/atmos11060639

John White, Jeppe Nielsen + Show 1 more

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https://doi.org/10.3390/atmos11060639

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Abstract

Fungal species composition and site of deposition within the airways affects whether diseases develop and where they may arise. The aim of this study is to obtain knowledge regarding the potential deposition of airborne culturable, viable, and non-viable fungi in the airways of pig farm workers, and how this composition changes over multiple sampling days. Airborne fungi were sampled using impactors and subsequently analyzed using amplicon sequencing and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) fingerprinting. The geometric mean aerodynamic diameter (Dg) of airborne particles with culturable airborne fungi were not affected by sampling days and ranged in size between 3.7 and 4.6 µm. Amplicon sequencing of the internal transcribed spacer region of the rRNA gene operon, in combination with DNA interchelating agents, revealed a large presence of non-viable fungi, but several pathogenic and toxic fungal species were detected in the viable portion. The diversity was found to be significantly associated with the sampling day but did not change significantly over multiple sampling rounds during the same day. The non-viable fraction contained genera typically associated with the pig gastrointestinal tract, such as Kazachstania and Vishniacozyma. In conclusion, the Dg of culturable fungi was between 3.7 and 4.6 µm, and the Dg of the viable and total fungi was 1.5 and 2.1 µm, respectively. The species composition changed over the multiple sampling days.

Highlights

Pig farmers are exposed to high concentrations of bioaerosols, ammonia, and other noxious compounds, all of which can contribute to the development or exacerbation of existing airway problems [1,2]
38.3% to 69.5% relative humidity (RH), respectively, with the coolest temperatures recorded during the winter and the hottest during the summer (Table 1)
On the 19th of June and 17th of July, the stables and pigs were misted several times during the study, which resulted in the relative humidity being highest on those days

Summary

Introduction

Pig farmers are exposed to high concentrations of bioaerosols, ammonia, and other noxious compounds, all of which can contribute to the development or exacerbation of existing airway problems [1,2]. Exposure to airborne fungi by pig farm workers has not been as well characterized even though exposure to fungi is known to be linked to the development of asthma, allergic sensitization, or other hypersensitivity disorders [3]. In particular for airborne fungi, the place of deposition of different fungal species in the human airways has an impact on the health effects they may cause [4,5,6]. Size-fractioned aerosols, based on their aerodynamic diameter, are routinely used to understand where in the airways aerosols may deposit. The ACI-6 size fractionates particles into six health relevant sizes, allowing researchers to quickly detect the culturable microorganisms present. Less used than the Atmosphere 2020, 11, 639; doi:10.3390/atmos11060639 www.mdpi.com/journal/atmosphere

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