High-Flow-Rate Impinger for the Study of Concentration, Viability, Metabolic Activity, and Ice-Nucleation Activity of Airborne Bacteria

Abstract

The study of airborne bacteria relies on a sampling strategy that preserves their integrity and in situ physiological state, e.g. viability, cultivability, metabolic activity, and ice-nucleation activity. Because ambient air harbors low concentrations of bacteria, an effective bioaerosol sampler should have a high sampling efficiency and a high airflow. We characterize a high-flow-rate impinger with respect to particle collection and retention efficiencies in the range 0.5-3.0 μm, and we investigated its ability to preserve the physiological state of selected bacterial species and seawater bacterial community in comparison with four commercial bioaerosol samplers. The collection efficiency increased with particle size and the cutoff diameter was between 0.5 and 1 μm. During sampling periods of 120-300 min, the impinger retained the cultivability, metabolic activity, viability, and ice-nucleation activity of investigated bacteria. Field studies in semiurban, high-altitude, and polar environments included periods of low bacterial air concentrations, thus demonstrating the benefits of the impinger's high flow rate. In conclusion, the impinger described here has many advantages compared with other bioaerosol samplers currently on the market: a potential for long sampling time, a high flow rate, a high sampling and retention efficiency, low costs, and applicability for diverse downstream microbiological and molecular analyses.

Microbial dispersal limitation to isolated soil habitats in the McMurdo Dry Valleys of Antarctica

“…At each station and time interval air flow rates of 300L/min were employed for 4hrs into 15ml RNA later . This approach overcomes limitations from earlier studies where low volume pumps have necessitated long sampling durations with uncertain microbial survival and recovery and impaction techniques that are known to bias against certain phyla 2,6 . Non-polar air samples were collected from New Zealand’s North Island (36.916153 S, 174.645760 E) during the same austral summer season and using the same method.…”

Bioaerosol field measurements: Challenges and perspectives in outdoor studies

“…Another implication of the low biomass is the high susceptibility to contamination. Aside from high sample volumes, good practices include stringent cleaning, sterilization, or baking of the sampling equipment (Dommergue et al 2019;Santl-Temkiv et al 2017;Santl-Temkiv et al 2018;Lever et al 2015), sterile techniques when handling and analyzing the samples ( Santl-Temkiv et al 2013; Temkiv et al 2012) as well as performing periodical handling-and operational blanks to verify that measurements are not influenced by contamination (Dommergue et al 2019;Santl-Temkiv et al 2017;Temkiv et al 2012). Finally, using real-time samplers (e.g., fluorescence or mass spectrometric analyzers) as a component of the study can complement other work by providing qualitative or semi-quantitative results at a much higher time resolution (Huffman et al 2019).…”

Atmospheric Processing and Variability of Biological Ice Nucleating Particles in Precipitation at Opme, France

“…For investigating the processing, i.e., the specific behavior, of INPs in the atmosphere, we statistically compared our data with others measurements carried out at nearby, at puy de Dôme Mountain Observatory (1465 m a.s.l. ), in clouds and aerosols in the frame of other studies [6,30,32]. In addition, INP concentration measurements were carried out on aerosols collected on a weekly basis in 2012 on quartz filter at the same site to account for different sampling methods.…”

“…This demonstrates some extent of partitioning of INPs in the atmosphere depending on the temperature at which INPs catalyze ice formation, and involving water condensation, freezing and precipitation. In addition of data generated in this study on precipitation and aerosols collected by filtration (see Table S4 and Figure S4 for data), literature data were retrieved for cloud water and aerosols collected by impingement from [6,32], respectively (studies led at puy de Dôme summit, i.e., a few km away from the sampling site investigated here). The average normalized freezing profile of ice-nucleation active (INA) bacteria isolated from clouds previously [11] is also shown for comparison.…”