Bioaerosol sampling is an essential and integral part of any bioaerosol investigation. Since bioaerosols are very diverse in terms of their sizes, species, biological properties, and requirements f...

Bioaerosol sampling: Classical approaches, advances, and perspectives

Fungal spores and mycelium fragments are particles which become and remain airborne and have been subjects of aerobiological studies. The presence and the abundance of taxa in aerobiological samples can be very variable and impaired by changeable climatic conditions. Because many fungi produce mycotoxins and both their mycelium fragments and spores are potential allergens, monitoring the presence of these taxa is of key importance. So far data on exposure and sensitization to fungal allergens are mainly based on the assessment of few, easily identifiable taxa and focused only on certain environments. The microscopic method used to analyze aerobiological samples and the inconspicuous fungal characters do not allow a in depth taxonomical identification. Here, we present a first assessment of fungal diversity from airborne samples using a DNA metabarcoding analysis. The nuclear ITS2 region was selected as barcode to catch fungal diversity in mixed airborne samples gathered during two weeks in four sites of North-Eastern and Central Italy. We assessed the taxonomic composition and diversity within and among the sampled sites and compared the molecular data with those obtained by traditional microscopy. The molecular analyses provide a tenfold more comprehensive determination of the taxa than the traditional morphological inspections. Our results prove that the metabarcoding analysis is a promising approach to increases quality and sensitivity of the aerobiological monitoring. The laboratory and bioinformatic workflow implemented here is now suitable for routine, high-throughput, regional analyses of airborne fungi.

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DNA metabarcoding uncovers fungal diversity of mixed airborne samples in Italy

The impact of bioaerosol emissions from urban, agricultural and industrial environments on local air quality is of growing policy concern. Yet the risk exposure from outdoor emissions is difficult to quantify in real-time as microbial concentration in air is low and varies depending on meteorological factors and land use types. While there is also a large number of sampling methods in use, there is yet no standardised protocol established. In this review, a critical insight into chemical fingerprint analysis of microbial volatile organic compounds (MVOC) is provided. The most suitable techniques for sampling and analysing MVOCs in outdoor environments are reviewed and the need for further studies on MVOCs from outdoor environments including background levels is highlighted. There is yet no rapid and portable technique that allows rapid detection and analysis of MVOCs on site. Further directions towards a portable GC–MS coupled with SPME or an electronic nose are discussed.

Fingerprinting outdoor air environment using microbial volatile organic compounds (MVOCs) – A review

In this review, the problem of microbiological infestation of buildings was discussed. The techniques of detection were described as well, with special attention drawn to the rapid-early detection methods based on gas sensor arrays. The physical and chemical conditions of the building environment conducive to the development of microorganisms and the technical conditions influencing the problem of microbiological infestation were investigated. Additionally, the harmful effects on human health caused by the microbiological contamination were discussed, with a short review of particular groups of microorganisms causing sick building syndrome. Among the detection techniques, the traditional microbiological techniques as well as the molecular and chemical methods were presented. Different designs of the gas sensor arrays together with the various techniques of analyzing the received multidimensional signal were described, analyzed, and compared in detail.

Methods for Early Detection of Microbiological Infestation of Buildings Based on Gas Sensor Technologies

Particulate matters (PMs), e. g. dusts, fibres, smokes, fumes, mists, liquid droplets and airborne respirable solid or liquid particles, are the major sources of air pollution concerning outdoor and indoor air quality. Among various PMs, bioaerosols are airborne particles that are either living organisms (bacteria, viruses, and fungi) or originate from living organisms (endotoxin, allergen, etc). PMs and/or bioaerosols have adverse health effects of infection, allergy, and irritation. Proper management and source identification of PMs and bioaerosols will reduce their negative health impact. In this review, we will discuss the analytical technologies and sensors for PMs and bioaerosols. We will first introduce four types of PM analysers, namely, filter-based gravimetric method (GMM), optical method, s-ray absorption method (BAM), and tapered element oscillating microbalance (TEOM). We will provide examples of how commercial PM analyzers of different principles have been compared and calibrated for specific applications under different climate conditions of specific geographic locations. For bioaerosols, having more complex biological and biochemical identity, we will start from air sampling techniques, followed by a discussion of various detection methods (plate culture, molecular methods, immunoassays and biosensors) in association with compatible sampling technologies. Using Influenza A (H1âN1) virus and SARS-CoV-2 (COVID-19) virus as examples, we have highlighted air sampling and detection challenges for viral aerosols relative to bacterial and fungal aerosols. Finally, we provide a perspective for future trends according to the limitation of current commercial products and the key challenges in this field.

Sensors and Analytical Technologies for Air Quality: Particulate Matters and Bioaerosols.

The threat of bioterrorism and pandemics has highlighted the urgency for rapid and reliable bioaerosol detection in different environments. Safeguarding against such threats requires continuous sampling of the ambient air for pathogen detection. In this study we investigated the efficacy of the Airborne Sample Analysis Platform (ASAP) 2800 bioaerosol sampler to collect representative samples of air and identify specific viruses suspended as bioaerosols. To test this concept, we aerosolized an innocuous replication-defective bovine adenovirus serotype 3 (BAdV3) in a controlled laboratory environment. The ASAP efficiently trapped the surrogate virus at 5 × 10(3) plaque-forming units (p.f.u.) [2 × 10(5) genome copy equivalent] concentrations or more resulting in the successful detection of the virus using quantitative PCR. These results support the further development of ASAP for bioaerosol pathogen detection.

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Elizabeth Clark

Papers

Efficiency of Airborne Sample Analysis Platform (ASAP) bioaerosol sampler for pathogen detection