10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Aerosolization of Biological Aerosols: Principles and Pitfalls
GEDIMINAS MAINELIS, Huajun Zhen, Taewon Han, Rutgers, The State University of New Jersey
Abstract Number: 1039 Working Group: Bioaerosols
Abstract Bioaerosol generation is an important aspect of bioaerosol research, and reliable and robust methods are needed to produce steady bioaerosol streams of desired concentrations with minimum damage or other negative effects to the aerosolized biological particles.
This presentation will focus on liquid-based bioaerosol generation techniques and will explore the main principles of commonly used devices, such as various atomizers and bubbling-based bioaerosol. The talk will then explore pitfalls of bioaerosol generation, namely potential damage to bacterial and fungal cells and various options for minimizing such damage. As a case in point, the effect on culturability and membrane integrity Escherichia coli when aerosolized by four different devices will be explored. Here, Collison nebulizer, a Liquid-Sparging Aerosolizer (LSA), a C-flow nebulizer, and a recently-designed Single-Pass Aerosolizer (SPA), which is a single-pass pneumatic nebulizer, aerosolized E. coli under different device regimes.
The extent of cell membrane damage was determined as the Cell Membrane Damage Index, which was expressed as the ratio of cell-released 16S rRNA gene copies in sample liquid versus the entire amount of 16S rRNA gene copies in a bioaerosol sample. The Damage Indices for E. coli aerosolized with the Collison and C-flow nebulizers at 40 psi were significantly higher than the corresponding Indices at nebulization pressures of 5 and 15 psi. However, the increased aerosolization pressure for LSA and SPA did not have a substantial impact on cell membrane damage. Collison nebulizer and SPA were observed to cause increased culturability loss with increased aerosolization pressure (5 to 15 psi for Collision nebulizer and 5 to 40 psi for SPA), while the other two generators did not increase the loss of culturability with increased aerosolization pressure. At a constant aerosol concentration of 100 bacteria/cm3, the SPA showed the highest bacterial culturability among the tested generators. Only the Collison nebulizer and SPA achieved aerosol concentrations of 1000 bacteria/cm3, and the SPA outperformed the Collison nebulizer with respect to cell membrane damage. In another aspect of this investigation, a fraction of particles <0.523 µm, i.e., fragments of bacteria, increased for all devices with increasing aerosolization pressure. Overall, the results demonstrate that the extent of cell damage due to aerosolization could be managed by selecting different aerosolization techniques and by carefully choosing operational parameters of those techniques.