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Bactericidal action of positive and negative ions in air

By L.A. Fletcher, L.F. Gaunt, Clive B. Beggs, Simon J. Shepherd, P.A. Sleigh, C.J. Noakes and Kevin G. Kerr

Abstract

In recent years there has been renewed interest in the use of air ionisers to control of the spread of airborne infection. One characteristic of air ions which has been widely reported is their apparent biocidal action. However, whilst the body of evidence suggests a biocidal effect in the presence of air ions the physical and biological mechanisms involved remain unclear. In particular, it is not clear which of several possible mechanisms of electrical origin (i.e. the action of the ions, the production of ozone, or the action of the electric field) are responsible for cell death. A study was therefore undertaken to clarify this issue and to determine the physical mechanisms associated with microbial cell death.\ud In the study seven bacterial species (Staphylococcus aureus, Mycobacterium parafortuitum, Pseudomonas aeruginosa, Acinetobacter baumanii, Burkholderia cenocepacia, Bacillus subtilis and Serratia marcescens) were exposed to both positive and negative ions in the presence of air. In order to distinguish between effects arising from: (i) the action of the air ions; (ii) the action of the electric field, and (iii) the action of ozone, two interventions were made. The first intervention involved placing a thin mica sheet between the ionisation source and the bacteria, directly over the agar plates. This intervention, while leaving the electric field unaltered, prevented the air ions from reaching the microbial samples. In addition, the mica plate prevented ozone produced from reaching the bacteria. The second intervention involved placing an earthed wire mesh directly above the agar plates. This prevented both the electric field and the air ions from impacting on the bacteria, while allowing any ozone present to reach the agar plate. With the exception of Mycobacterium parafortuitum, the principal cause of cell death amongst the bacteria studied was exposure to ozone, with electroporation playing a secondary role. However in the case of Mycobacterium parafortuitum, electroporation resulting from exposure to the electric field appears to have been the principal cause of cell inactivation.\ud The results of the study suggest that the bactericidal action attributed to negative air ions by previous researchers may have been overestimated

Topics: Bactericidal Action, Ions, Air
Year: 2007
OAI identifier: oai:bradscholars.brad.ac.uk:10454/581
Provided by: Bradford Scholars

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Citations

  1. (1999). AJ: Sensitivity of Candida albicans to negative air ion streams. doi
  2. GM: Cluster airion effects on bacteria and moulds: 21 September; Ilmenau,
  3. GM: Cluster airion effects on bacteria and moulds: 21 September; Ilmenau, Germany .
  4. (2002). Hughes JF: Bactericidal effects of negative and positive ions generated in nitrogen on Escherichia coli. doi
  5. (2003). Hughes JF: Bactericidal effects of negative and positive ions generated in nitrogen on starved Pseudomonas veronii . doi
  6. (2006). JG: Transient electrical field across cellular membranes: pulsed electric field treatment of microbial cells. doi
  7. (1979). Kreuger AP: Superoxide involvement in the bactericidal effects of negative air ions on Staphylococcus albus. Nature doi
  8. (1964). MW: Effects of air ions on bacterial aerosols. doi
  9. (1960). RW: Some effects of ionized air on Penicillium notatum. doi
  10. (1955). Studies on ionization effects .
  11. (2006). Taylor CC: Air ionisation and colonisation/ infection with methicillin-resistant Staphylococcus aureus and Acinetobacter species in an intensive care unit. Intensive Care Med doi
  12. (2006). Transient electrical field across cellular membranes: pulsed electric field treatment of microbial cells. doi

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