Characterization of Exposure to Molds and Actinomycetes in Agricultural Dusts by Scanning Electron Microscopy, Fluorescence Microscopy and the Culture Method

Air samples from 79 farms with 10^5 to 10^11 microorganisms/m^3 were analyzed by scanning electron microscopy (SEM), fluorescence microscopy (FM), and the culture method. The total exposure to micro organisms (particularly actinomycetes) was under estimated when assessed as colony-forming units (cfu). The average cfu count was one-sixth of the total count according to SEM or FM, and the individual variability was great. This occurrence was partly explained by the aggregation of spores. Single spores accounted for 2-65 % of all spores in 35 samples. There was an average of three spores/particle, and 93 (rang e 67-100) % of the spore s were single or in aggregates of respire able size. Aggregation was more pronounced for actinomycetes and at high spore counts. Actinomycetes and bacteria could not be distinguished by FM. Bacteria (other than actinomycetes) were not detected by SEM, yet the total count of microorganisms was similar for FM and SEM. Most particles were spores from actinomycetes and fungi of the genera Aspergillus or Penicillium.

並列關鍵字

air sampling ； allergic alveolitis ； bacteria ； microorganisms ； mold spores ； organic dust ； spores

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