Assessing the airborne survival of bacteria in populations of aerosol droplets with a novel technology

Abstract

The airborne transmission of infection relies on the ability of pathogens to survive aerosol transport as they transit between hosts. Understanding the parameters that determine the survival of airborne microorganisms is critical to mitigating the impact of disease outbreaks. Conventional techniques for investigating bioaerosol longevity in vitro have systemic limitations that prevent the accurate representation of conditions that these particles would experience in the natural environment. Here, we report a new approach that enables the robust study of bioaerosol survival as a function of relevant environmental conditions. The methodology uses droplet-on-demand technology for the generation of bioaerosol droplets (1 to greater than 100 per trial) with tailored chemical and biological composition. These arrays of droplets are captured in an electrodynamic trap and levitated within a controlled environmental chamber. Droplets are then deposited on a substrate after a desired levitation period (less than 5 s to greater than 24 h). The response of bacteria to aerosolization can subsequently be determined by counting colony forming units, 24 h after deposition. In a first study, droplets formed from a suspension of Escherichia coli MRE162 cells (10 8 ml 21 ) with initial radii of 27.8 + 0.08 mm were created and levitated for extended periods of time at 30% relative humidity. The time-dependence of the survival rate was measured over a time period extending to 1 h. We demonstrate that this approach can enable direct studies at the interface between aerobiology, atmospheric chemistry and aerosol physics to identify the factors that may affect the survival of airborne pathogens with the aim of developing infection control strategies for public health and biodefence applications.royalsocietypublishing.org/journal/rsif J. R. Soc. Interface 16: 20180779

The global impact of bacterial processes on carbon mass

“…Several studies report total concentrations of bacterial cells in the atmosphere, whereas others present only the concentration of viable cells. The complexity of distinguishing viable, cultivable, and dead bacterial cells in the atmosphere has been discussed in several studies (Burrows et al, 2009a;Otero Fernandez et al, 2019). We assume in Sect.…”

The global impact of bacterial processes on carbon mass

“…In addition, the large discrepancy in reported Flive between < 0.1% up to nearly 100% as discussed e.g., by Lindeman et al (1982), Lighthart and Shaffer (1994) and Gandolfi et al (2013), might be 255 also due to differences in the measurement techniques. Consistent experimental methodologies are needed to give comprehensive data on Flive and the survival rates of bacteria in aerosol particles (Otero Fernandez et al, 2019). Approximating the total mass by doubling the carbon mass, results in 34 fg cell -1 , i.e.…”

“…The atmospheric lifetime of bacteria cells is limited to several minutes (Otero Fernandez et al, 2019) to hours (Amato et al, 2015). Several studies report total concentrations of bacteria cells in the atmosphere whereas others present only 95 the concentration of viable cells.…”

“…Several studies report total concentrations of bacteria cells in the atmosphere whereas others present only 95 the concentration of viable cells. The complexity of distinguishing viable, cultivable and dead bacteria cells in the atmosphere has been discussed in several studies (Burrows et al, 2009a;Otero Fernandez et al, 2019). ; (Morris et al, 2000) i (Copeland et al, 2015); j (Stibal and Elster, 2005); k (Middelboe, 2000) ; l (Fuchs et al, 2000) 105 https://doi.org/10.5194/acp-2019-619 Preprint.…”

Drying kinetics and nucleation in evaporating sodium nitrate aerosols

“…Understanding the evaporative drying and crystallisation of aerosol droplets is important for a broad range of industrial applications, most notably in spray-drying 1 , and for predicting the optical and physical properties of atmospheric aerosols 2 . The microphysics of the drying process also likely has an impact on the viability of bacteria in aerosols 3 . In spray drying the goal is to control the distribution of sizes, morphology and phase of the final droplets, which are very sensitive to processing conditions such as solvent 4,5 , temperature [6][7][8] , pH 9,10 and additional co-excipients [11][12][13] .…”