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.
Highlights
Mould are a wide range of fungal organisms that flourish under damp conditions indoors and outdoors, and in humans exposure is linked to the exacerbation of asthma, allergic rhinitis and occasionally infection [1], but requires additional investigation [2].A review of the current literature suggests there is no universally accepted method for detecting, identifying and/or enumerating fungi within buildings, and a lack of universally accepted limits for maximum permissible and/or normal exposure to occupants, or even what may constitute a ‘mouldy’ house [3].Outdoors, various moulds, yeasts, various other fungi and organisms saprophytically degrade organic matter such as fallen leaves, trees, etc., and are generally ecologically beneficial
PeptoneCG had fewer colony forming units (CFU) than SabCG ‘stock’ and ‘from scratch’, but comparable CFU to MaltosePeptoneCG and GlucoseMaltosePeptoneCG
The results indicated that the presence of maltose reduced the numbers of CFU detected, being similar to PeptoneCG despite the noted degree of hydrolysis of maltose to glucose
Summary
Mould are a wide range of fungal organisms that flourish under damp conditions indoors and outdoors, and in humans exposure is linked to the exacerbation of asthma, allergic rhinitis and occasionally infection [1], but requires additional investigation [2]. Various moulds, yeasts, various other fungi and organisms saprophytically degrade organic matter such as fallen leaves, trees, etc., and are generally ecologically beneficial. The most common outdoor mould & yeast genera/types noted in studies in the Northern. A comparison of several media types to assess outdoor airborne fungi in Melbourne, Australia materials to author WDB. No additional external funding was received for this study
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