Aerosolisation of Escherichia coli and associated endotoxin using an improved bubbling bioaerosol generator

Experimental bioaerosol generators are widely used in scientific studies. However, the choice of such a generator for a given application is made difficult by the lack of information on the performances or limits of these systems. In this article, we venture the assumption that a bubbling liquid generator constitutes a promising choice to produce experimental bioaerosols with known and controlled characteristics. A generator inspired by the Liquid Sparging Aerosolizer (LSA) developed by Mainelis et al. (2005) was used to aerosolise microorganisms by bubbling compressed air through a bacterial suspension film. mances of a modified LSA-type bubbling generator were evaluated. The generated bioaerosols were characterised, in particular in terms of concentrations, stability over time and reproducibility. The possibility to produce controlled airborne endotoxin concentrations from gram-negative bacterial suspensions was also investigated. rig to generate and characterise experimental bioaerosols was designed. Tests were performed on standardised Escherichia coli suspensions, stable over time, showing cultivable bacteria concentrations between 1.5×108 and 3.0×108 CFU mL−1. In the operating conditions evaluated, the generator provided aerosol concentrations in the following ranges: 4.0×105–1.0×109 Cell m−3 total bacteria, 2.5×104–2.0×107 CFU m−3 cultivable bacteria and 20–15,000 EU m−3 endotoxins. Bioaerosol properties were stable throughout generation (180 min) and were satisfactorily reproducible between tests. Bioaerosol generation was controllable, making these experimental bioaerosols appropriate for various laboratory assays, including work requiring the use of airborne endotoxins at known concentrations. Data on both the physical and biological properties of the bioaerosol, and very complete information on the generation systemʹs performance were obtained. The influences of parameters such as airflow rate, height of liquid film or concentration of the bacterial suspension were also evaluated. These parameters can be used to adjust the bioaerosol to the needs of the experiment.