Non-culturable bioaerosols in indoor settings: Impact on health and molecular approaches for detection

Abstract

h i g h l i g h t sNon-culturable fraction of bioaerosols is important but still misunderstood. Airborne non-culturable agents can be hazardous for human respiratory health. Molecular tools allow the detection of airborne non-culturable microorganisms. Culture-dependent and independent tools should be used for bioaerosol studies. Several research needs relating to non-culturable agents must be addressed. a b s t r a c tDespite their significant impact on respiratory health, bioaerosols in indoor settings remain understudied and misunderstood. Culture techniques, predominantly used for bioaerosol characterisation in the past, allow for the recovery of only a small fraction of the real airborne microbial burden in indoor settings, given the inability of several microorganisms to grow on agar plates. However, with the development of new tools to detect non-culturable environmental microorganisms, the study of bioaerosols has advanced significantly. Most importantly, these techniques have revealed a more complex bioaerosol burden that also includes non-culturable microorganisms, such as archaea and viruses. Nevertheless, air quality specialists and consultants remain reluctant to adopt these new researchdeveloped techniques, given that there are relatively few studies found in the literature, making it difficult to find a point of comparison. Furthermore, it is unclear as to how this new non-culturable data can be used to assess the impact of bioaerosol exposure on human health. This article reviews the literature that describes the non-culturable fraction of bioaerosols, focussing on bacteria, archaea and viruses, and examines its impact on bioaerosol-related diseases. It also outlines available molecular tools for the detection and quantification of these microorganisms and states various research needs in this field.

Galvanic microcells as control agent of indoor microorganisms

“…The 2001 National Human Activity Pattern Survey estimated that people in developed countries spend nearly 90% of their time indoors and that time spent indoors has remained fairly uniform over the past few decades2. Humans share indoor spaces with diverse populations of microorganisms from all three domains that create bioaerosols3 and colonize indoor surfaces. Fungal contamination of indoor ecosystems has always been of interest in connection to building structure biodeterioration and serious effects on human health4.…”

Optimization of PMA-qPCR forStaphylococcus aureusand determination of viable bacteria in indoor air

“…Bacterial counts greater than 10 5 cells/m 3 were occasionally detected from the recreation area in the basement and the waste storage site outdoors (Table ). Viable bacteria may produce fragments, for example, peptidoglycans and endotoxins, that could cause allergy and inflammation in humans . In addition, high quantities of viable bacteria imply a poor IAQ; indeed, a ceiling limit of 1500 CFU/m 3 has been set for bacterial aerosols as the mandatory IAQ standard of Taiwan .…”

“…The optimized PMA‐qPCR method was then applied to air samples collected from various environments to determine the airborne S. aureus counts and assess the feasibility of PMA‐qPCR for field samples. The total counts of viable bacterial bioaerosols were also measured by PMA‐qPCR, considering their implications in human health and indoor air quality (IAQ) . The percentage of S. aureus in relation to total viable bacteria was calculated.…”

Bioaerosol sampling: sampling mechanisms, bioefficiency and field studies

“…53 A lack of bioaerosol studies targeting viruses and archea has also been identified, further limiting our understanding of the impact of airborne microbes on human health. 123 Several of the studies discussed in this review were based in bioaerosol-emitting facilities, such as WWTP and compost facilities, where the exposure to harmful microbes is a cause for concern for occupational safety reasons and for risk to health of the population in the surrounding area. In such cases the task for current research is to establish suitable doseeresponse relationships to enable health-based exposure limits for bioaerosols to be derived.…”