Collection of Airborne Microorganisms into Liquid by Bubbling through Porous Medium

摘要

A new method for the removal of airborne particles by air bubbling through fibrous filters immersed into a liquid has recently been developed (Agranovski et al. 1999) and shown to be very efficient for cleaning air environment swith ultra-fine aerosol particles. The principal objective of the present study was to evaluate the new bubbling technique for the collection of airborne bacteria into a liquid for subsequent physical and microbiological analysis. It was found that the technique is capable of achieving a physical collection efficiency of 98.5 or higher for particles larger than 0.3 #mu#m in aerodynamic diameter. The physical collection efficiency of the prototype bubbler remained at that high level for 8 h of continuous operation with negligible variation of the pressure drop across the device. Evaporation of the collection fluid did not exceed 20 during 8 h, and the reaerosolization effect on the physical collection efficiency of the bubbler prototype was < 8. The recovery rate of gram-negative Pseudomonas fluorescens bacteria collected for 20 min was shown to be as high as 74 (+-) 10. Its decrease with time was not statistically significant: the recovery rate reached 63 (+-) 15 and 58 (+-) 16 after 4 and 8 h of continuous operation, respectively. Thus the bubbling technique was demonstrated to be suitable for collecting viable airborne bacteria even if they are sensitive to the stress.