Development and optimization of Stationary Electrostatic Bioaerosol Sampler (SEBS) for viable and culturable airborne microorganisms

This study focused on developing and testing a stationary electrostatic bioaerosol collector with a high concentration rate while preserving viable and culturable microorganisms. Using our earlier advances in the electrostatic collection of airborne microorganisms, we designed and optimized a Stationary Electrostatic Bioaerosol Sampler (SEES), which incorporates our previously developed wire-to-wire charger and a newly-designed removable particle collector. The sample elution system was also redesigned and optimized to achieve a practical solution yielding a high sample concentration rate. The sampler's collector and its hydrophobic coating methods, collection voltages, and material of sample removal tubes were optimized through an iterative process. SEES is a two-stage electrostatic sampler with a wire-to-wire charger and a stainless steel collection electrode coated using polydimethylsiloxane (PDMS) coating technique and ultraviolet/ozone surface treatment method. The entire collected sample is eluted into 0.2 or 1 mL of sterile phosphate-buffered saline (PBS) using a customized particle removal system made of glass. The developed SEES was operated at 20 L/min; its physical and biological performance was compared to the Button filter sampler (SKC, Inc.) when sampling two airborne bacteria and two fungi in the laboratory. On average, SEES showed actual physical collection efficiency of similar to 50% when samples were eluted into 0.2 mL; the efficiency increased to similar to 75% when 1 mL elution liquid was used. The average relative viability efficiency reached similar to 80%, suggesting that the sampling stress was reduced compared to the filter sampler. The relative culturability efficiency was similar to 60%. The use of 0.2 mL elution liquid resulted in a sample concentration rate of similar to 5 x 10(4) min(-1), which will enable faster detection and determination of viable and culturable bioaerosols, especially when sampling in low concentration environments. Future studies will evaluate SEBS' s performance and utility in field studies.

Automated summary

This study developed and tested a stationary electrostatic bioaerosol collector with a high concentration rate while preserving viable and culturable microorganisms. The collector showed comparable physical collection efficiency to the filter sampler, with increased viability and culturability efficiency. The elution liquid volume and hydrophobic coating method were optimized to achieve a sample concentration rate of 5 x 10⁴ min⁻¹, enabling faster detection of bioaerosols.