Evaluation of Impingement and Filtration Methods for Fungal Bioaerosol Sampling

• Main Authors: Lin, Wen-Hai, 林文海
• Other Authors: Li Chih-Shan
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/09403329463269258999

博士 === 國立臺灣大學 === 公共衛生研究所 === 86 === The influences of sampling time and flow rates as well as sample storage on total recovery of fungal bioaerosols were evaluated in the laboratory test chamber by three sampling methods: AGI-30 all glass impingers, Nucleporefiltration and elution method, and the gelatin filters. A Pitt-3 generator anda Collison nebulizer aerosolized spores of Penicillium citrinum and cells ofCandida famata var. flareri, respectively. The results demonstrated that total recovery of spores collected by the AGI-30 impinger was in the range of 4% to 24%.Moreover, the average totalrecoveries of spores collected by Nuclepore and gelatin filters were found to bein the rangeof 50% to 75%, and 50% to 90%, respectively.The observed low totalrecovery for AGI-30 impinger was primary due to the biological stress during sampling process. The total recovery of fungal sporescollected in AGI-30impingers became lower as the sampling time and flow ratesincreased. However,no significant influences of sampling time and flow rateson the total recovery of both Nuclepore filtration and gelatin-filter methodswere observed. In summary, it was found that filtration methods could performmuch better than impingers for sampling airborne fungal spores. To provide a quantitative basis for determining the airborne yeastconcentration, thebioefficiency results demonstrated that the total recovery ofairborne yeast collectedby the AGI-30 impinger was above 80% at 70% relativehumidity, while decreasedrapidly as relative humidity decreased beheath 60%. This might be relatedto undergoing desiccation and losing culturability before collection for yeastcells following bioaerosol generation from liquid suspension. The filtrationoutcome indicated that dehydration effect was significant and total recoverywas less than 20% for Nuclepore and gelatin filters. In addition, no significanteffects were observed regarding sampling time and flow rates for these threesampling methods. Effects of storage time and temperature on the colony recovery of airborne fungal samples were evaluated in the same laboratory test chamber. The resultsdemonstrated that the bioefficiency of impinger for fungal spores decreased asstorage time increased whatever sampling time and flow rates were. In contrast,the yeast cells could survive in the impinger fluid and even utiliz additive tobud more cells. In addition, the inhibition effect of refrigerated samples wasobserved. Therefore, it was suggested that the samples collected by impingementmethod should be refrigerated and processed as soon as possible to avoid theloss of spore culturability and increase of yeast cells. Moreover, the effect of storage time filtration collection for fungal spores was demonstrated to beinsignificant. However, yeast recovery from filters was demonstrated to decreaseas storage time increased. It was concluded that the recovery would not decrease during storage if bioefficiencies of the sampling methods were excellent, forexample, using filters to collect fungal spores or impingers to collect yeastcells.