Feasibility of Generating Peaks of Bioaerosols for Laboratory Experiments

Abstract

Bioaerosol concentration peaks are frequently encountered in real-life atmospheres (indoor, outdoor, workplace, etc.), where they can be caused by several factors. However, evolution over time and variability of microbiological pollutant concentrations remain under-documented. The contribution of such peaks in the onset or the worsening of respiratory symptoms -in particular immuno-allergic reactions -has yet to be extensively studied. Although experimental bioaerosol generators are increasingly used, the intentional and controlled production of concentration peaks of biological agents has not yet been utilized in laboratory experiments. The main objective of this study was to show that it is possible to produce experimental bioaerosol concentration peaks with defined characteristics. Experiments were performed with a 'Liquid Sparging Aerosoliser'-type generator. With this system, peaks can be created by increasing the bubbling airflow through a film of bacterial (Escherichia coli) or fungal (Penicillium brevicompactum) liquid culture. The higher the set point value of the bubbling airflow, the greater the maximum bioaerosol concentration during the generated peak. Similarly, longer-lived peaks can be created by maintaining the increased airflow for a longer period of time. For both studied species, the relative size distribution was constant over time, regardless of modifications to the bubbling flow rate. The operator can monitor and control peak formation with this system thanks to real-time measurement of the number concentrations, targeting the appropriate particle size classes corresponding to diameters of the aerosolised microorganisms. This generator, characterized by gentle aerosolisation and a capacity to produce bioaerosol peaks, may contribute to enrich laboratory experiments for numerous applications.

Effects of Small-Size Suspended Solids on the Emission of Escherichia coli from the Aeration Process of Wastewater Treatment

“…2(a)), indicating the enhancement effects of kaolin clay. In general, bioaerosols generated for laboratory investigations are prepared as a pure solution containing only the test microorganisms (Simon and Duquenne, 2013). Therefore, it might be possible to enhance the generation of test bioaerosols by adding small-size nonfloc-type particles, such as kaolin clay, if the added particles will not affect the quality of the generated bioaerosols.…”

Poultry house as point source of intense bioaerosol emission

“…with the highest percentage contributions to the total microbiota -see above), i.e. from bacteria -staphylococci and enterococci with D ae from ~0.75 µm to ~1 µm, aerobic bacilli (Bacillus genus) and Gram-negative rods with D ae about ~0.8 µm, anaerobic bacilli (Clostridium genus) with D ae between 1.4-1.9 µm, actinomycetal species with D ae from 0.6 µm to 1.1 µm, as well as from fungi -Penicillium species with D ae from ~2.3 µm to ~3 µm, Aspergillus species, and from ~2.1 µm to ~3.6 µm, Cladosporium species with D ae about ~1.8 µm, Fusarium species with D ae between 4.35-6.8 µm [143][144][145][146][147], the size distribution analysis revealed that in case of airborne bacteria: a) the concentrations of bioaerosol particles in poultry house with 42-day-old chickens in all studied aerodynamic fractions, i.e. from 0.65 µm to above 7 µm, significantly augmented the concentrations recorded indoors with 7-day-old chickens, and when the poultry house was empty as well as those noted in outdoor (atmospheric) air (Scheffé tests: P < 0.01-0.001); b) when both 42-day-old and 7-day-old chickens were present indoors, the size distribution step plots had similar courses showing that bacteria in the air appeared mainly in the form of fine aggregates, composed solely of vegetative cells or spores and/or their aggregates with dust particles of D ae between 2.1-4.7 µm; c) when the poultry house was empty (i.e.…”

Viral, bacterial, and fungal contamination of Automated Teller Machines (ATMs)

“…having the highest percentage contributions to the total microbiotasee below), i.e. from bacteria -staphylococci and micrococci with d ae from ~0.75 µm to ~1 µm and from fungi -Penicillium and Aspergillus species with d ae from ~2.3 µm to ~3 µm and from ~2.1 µm to ~3.6 µm, respectively [41,42,43], such analysis revealed that bacteria appeared in the air mainly in the form of fine and coarse particulates composed of cells/ spores and/or their aggregates with dust particles, while fungi mainly as single conidia in the aerodynamic size range of 2.1-3.3 µm. If inhaled, bioaerosol composed of such particulates may reach and be deposited in case of bacteria within nasal and oral cavities, trachea, primary and secondary bronchi, in case of fungi within secondary bronchi.…”