Procedures for the characterisation of bioaerosol particles. Part II: Effects of environment on culturability

• Published in: Aerobiologia 2001-06, Vol.17 (2), p.109-119
• Main Authors: Griffiths, W D, Stewart, I W, Clark, J M, Holwill, IL
• Format: Article
• Language: English
• ISSN: 0393-5965
• DOI: 10.1023/A:1010820731625

The behaviour of bioaerosol particles in industrial and health-care applications may be most effectively understood once they have been quantitatively assessed using well-characterised sampling and assay techniques. However, the large number of different conditions possible in this wide range of applications makes the assessment of bioaerosol particles very difficult. In addition to the effects of different sampling and assay technologies, the mechanism of aerosolisation and environmental conditions can influence bioaerosol behaviour. The effects of sampler selection and suspension aerosolisation on bioaerosol viability were reported earlier as "Part I" of two papers, and the effects of the environment on the culturability of three different types of microorganism are reported here as "Part II". The environmental relative factors considered in the present study are: relative humidity (RH), aerosol-age, and a number of gaseous pollutants. A small number of additional tests, examining the effects of aerosolisation method on culturability, are also reported. A combination of an environmentally controlled Bioaerosol Test Chamber and Goldberg Rotating Drum were shown to be an appropriate facility to carry out the study. Changing RH was shown to have a considerable effect on the culturable fraction of aerosolised Sacharomyces cerevisiae cells but not Penicillium expansum spores or Bacillus subtilis var. niger spores. In this text, "culturable fraction" is defined as the fraction of the total number of microorganisms in a sample that will form colonies (i.e. grow and reproduce) on a suitably prepared culture plate under optimum conditions for the species of microorganism under consideration. After the initial shock of aerosolisation, the culturable fraction of S. cerevisiae cells and P. expansum spores is not further affected by increasing aerosol age. Results from an earlier study have shown spray suspension and collected aerosol age also have no effect on culturability of P. expansum spores. The effects of gaseous pollutants are reflected in the reduction in culturability of P. expansum spores following exposure to sulphur dioxide, ozone and ozone hydrocarbon cocktail. This reduction was never to less than 30% of the unpolluted control. All the tests show that P. expansum spores are fairly robust and biologically stable. Examination of the effects of aerosolisation technique on the culturability of S. cerevisiae shows the Collison nebuliser produces aerosols wi