A comparison of several media types and basic techniques used to assess outdoor airborne fungi in Melbourne, Australia

PLoS One. 2020 Dec 18;15(12):e0238901. doi: 10.1371/journal.pone.0238901. eCollection 2020.

Abstract

Despite the recent increase in interest in indoor air quality regarding mould, there is no universally accepted standard media for the detection of airborne fungi, nor verification of many commonly used techniques. Commonly used media including malt-extract agar (MEA), Sabouraud dextrose agar (Sab), potato dextrose agar (PDA) with and without antibiotics chloramphenicol & gentamycin (CG) were compared for their suitability in detecting a range of airborne fungi by collecting 150 L outdoor air on a number of different days and seasons via an Anderson 400-hole sampler in suburban Melbourne, Australia. There was relatively little variation in mean numbers of colony forming units (CFU) and types of fungi recovered between MEA, PDA, Sab media groups relative to variation within each group. There was a significant difference between Sab, Dichloran-18% glycerol (DG18) and V8® Original juice agar media, however. Antibiotics reliably prevented the growth of bacteria that typically interfered with the growth and appearance of fungal colonies. There was no significant evidence for a growth enhancing factor from potato, mineral supplements or various vegetable juices. Differing glucose concentrations had modest effects, showing a vague ideal at 2%-4% with peptone. Sanitisation of the aluminium Andersen 400-hole sampler top-plate by flame is possible, but not strictly required nor advisable. The use of SabCG as a standard medium was generally supported.

MeSH terms

  • Agar / metabolism
  • Air Microbiology
  • Air Pollution, Indoor / analysis
  • Australia
  • Colony Count, Microbial / methods
  • Culture Media / metabolism
  • Environmental Monitoring / methods
  • Fungi / growth & development*
  • Seasons

Substances

  • Culture Media
  • Agar

Grants and funding

Biotopia Environmental Assessment Pty Ltd provided support in the form of salary and materials to author WDB. The specific roles of this author is articulated in the ‘author contributions’ section. The funder had no commercial or vested interests in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding was received for this study.