Size-Fractionated Bioaerosol Collection in Liquid Medium with a Novel BioCascade Impactor

YUQIAO CHEN, Jiayi Chen, Sripriya Nannu Shankar, Stavros Amanatidis, Arantzazu Eiguren-Fernandez, John Lednicky, Chang-Yu Wu, University of Florida

     Abstract Number: 645
     Working Group: Aerosol Science of Infectious Diseases: What We Have Learned and Still Need to Know about Transmission, Prevention, and the One Health Concept

Abstract
Studies on the transmission mode of bioaerosols are hampered due to limitations of existing methods on size-fractionated collection and inability to maintain their viability. BioCascade, a novel size-fractionating sampler, collects particles based on their aerodynamic diameters (>10 μm, 4-10 μm and 1.5-4 μm for stages 1-3, respectively) onto Petri dishes containing liquid medium and could be paired with a gelatin filter (GF) or a condensation-based growth tube collector (CGTC) to collect particles <1.5 μm. We tested the performance of the BioCascade using aerosolized Saccharomyces kudriavzevii (5-6 µm). The aerosols were diluted with compressed air at a ratio of 1:3.5 and then collected by (1) BioCascade+CGTC; (2) BioCascade+GF; (3) CGTC and (4) GF. The colony forming units (CFU)/mL were 1.16×10⁴±3.90×10³ and 1.31×10⁴±5.92×10³ in the samples collected by stages 2 and 3 of BioCascade, respectively, the size range of which corresponds to the nominal size of S. kudriavzevii. The CFU/mL recorded in stage 1 (1.80×10³±5.83×10²) was ~6-7 times lower than that from stage 2 and 3. Experiments conducted with 2 mL of yeast suspension in PBS on a given stage and only PBS in successive stages demonstrated that there was no re-aerosolization within the stages of BioCascade. The ability of BioCascade to preserve the viability of bioaerosols collected was evaluated by exposing 2 mL of yeast suspension in PBS in the collector, to particle-free air. Gelatin filter, when paired with BioCascade as stage 4, did not collect viable S. kudriavzevii, while CGTC as stage 4 of BioCascade collected ~133 CFU/mL. In summary, the BioCascade can effectively collect viable S. kudriavzevii aerosols according to their particle size, maintain their viability (>80%), and have no re-aerosolization of collected S. kudriavzevii.