Viable airborne microbial counts from air-cooling units with and without complaints of urine and body odors

Ka Man LAI*, Yik Hei SUNG, Kowk Keung MA

*Corresponding author for this work

Research output: Journal PublicationsJournal Article (refereed)

2 Citations (Scopus)

Abstract

Viable airborne microbial counts are commonly used in indoor air quality (IAQ) assessment, but studies linking the microbial counts to a specific type of indoor microbial contamination are limited. We hypothesize that the airborne microbial counts can differentiate air-cooling units with and without complaints of urine and body odors. The keratinolytic property of some isolated bacteria prompts to the hypothesis that keratinase is present in the units to break down keratins, structural proteins that form human skin scales, as sources of amino acids and ammonium to produce the odors. Seven bacterial species and four fungal species were identified in the units and room air. Airborne Staphylococcus haemolyticus and Methylobacterium organophilum counts contributed the most to the microbial dissimilarities of units with and without odor complaints. Keratinolytic bacteria and a methylotrophic bacterium were abundant in the units. All the units contained ammonium, and keratinase activity was higher in the units with odor complaints. Extracellular keratinase activity was more effective at 20 °C than at 30 or 4 °C. Keratinolytic bacteria produced high levels of ammonium in the culture with skin cells. Viable airborne microbial counts can help IAQ inspectors to identify potential odor-causing air-cooling units. Keratins may be broken down in the units and associated with the odor complaints.

Original languageEnglish
Pages (from-to)229-241
Number of pages13
JournalAerobiologia
Volume33
Issue number2
Early online date23 Nov 2016
DOIs
Publication statusPublished - Jun 2017
Externally publishedYes

Fingerprint

urine
cooling
Air
odors
Urine
air
Ammonium Compounds
Indoor Air Pollution
Bacteria
air quality
keratin
bacteria
Keratins
skin (animal)
Methylobacterium organophilum
Staphylococcus haemolyticus
Methylobacterium
Skin
microbial contamination
structural proteins

Bibliographical note

We thank the HKBU Estate Office and Health and Safety team for assisting the field investigation and the Environment and Conservation Fund (Grant Ref.: ECF89/2015) for supporting this study.

Keywords

  • Air-conditioning systems
  • Bioaerosols
  • Indoor air quality
  • Microbial odor emission

Cite this

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abstract = "Viable airborne microbial counts are commonly used in indoor air quality (IAQ) assessment, but studies linking the microbial counts to a specific type of indoor microbial contamination are limited. We hypothesize that the airborne microbial counts can differentiate air-cooling units with and without complaints of urine and body odors. The keratinolytic property of some isolated bacteria prompts to the hypothesis that keratinase is present in the units to break down keratins, structural proteins that form human skin scales, as sources of amino acids and ammonium to produce the odors. Seven bacterial species and four fungal species were identified in the units and room air. Airborne Staphylococcus haemolyticus and Methylobacterium organophilum counts contributed the most to the microbial dissimilarities of units with and without odor complaints. Keratinolytic bacteria and a methylotrophic bacterium were abundant in the units. All the units contained ammonium, and keratinase activity was higher in the units with odor complaints. Extracellular keratinase activity was more effective at 20 °C than at 30 or 4 °C. Keratinolytic bacteria produced high levels of ammonium in the culture with skin cells. Viable airborne microbial counts can help IAQ inspectors to identify potential odor-causing air-cooling units. Keratins may be broken down in the units and associated with the odor complaints.",
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author = "LAI, {Ka Man} and SUNG, {Yik Hei} and MA, {Kowk Keung}",
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Viable airborne microbial counts from air-cooling units with and without complaints of urine and body odors. / LAI, Ka Man; SUNG, Yik Hei; MA, Kowk Keung.

In: Aerobiologia, Vol. 33, No. 2, 06.2017, p. 229-241.

Research output: Journal PublicationsJournal Article (refereed)

TY - JOUR

T1 - Viable airborne microbial counts from air-cooling units with and without complaints of urine and body odors

AU - LAI, Ka Man

AU - SUNG, Yik Hei

AU - MA, Kowk Keung

N1 - We thank the HKBU Estate Office and Health and Safety team for assisting the field investigation and the Environment and Conservation Fund (Grant Ref.: ECF89/2015) for supporting this study.

PY - 2017/6

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N2 - Viable airborne microbial counts are commonly used in indoor air quality (IAQ) assessment, but studies linking the microbial counts to a specific type of indoor microbial contamination are limited. We hypothesize that the airborne microbial counts can differentiate air-cooling units with and without complaints of urine and body odors. The keratinolytic property of some isolated bacteria prompts to the hypothesis that keratinase is present in the units to break down keratins, structural proteins that form human skin scales, as sources of amino acids and ammonium to produce the odors. Seven bacterial species and four fungal species were identified in the units and room air. Airborne Staphylococcus haemolyticus and Methylobacterium organophilum counts contributed the most to the microbial dissimilarities of units with and without odor complaints. Keratinolytic bacteria and a methylotrophic bacterium were abundant in the units. All the units contained ammonium, and keratinase activity was higher in the units with odor complaints. Extracellular keratinase activity was more effective at 20 °C than at 30 or 4 °C. Keratinolytic bacteria produced high levels of ammonium in the culture with skin cells. Viable airborne microbial counts can help IAQ inspectors to identify potential odor-causing air-cooling units. Keratins may be broken down in the units and associated with the odor complaints.

AB - Viable airborne microbial counts are commonly used in indoor air quality (IAQ) assessment, but studies linking the microbial counts to a specific type of indoor microbial contamination are limited. We hypothesize that the airborne microbial counts can differentiate air-cooling units with and without complaints of urine and body odors. The keratinolytic property of some isolated bacteria prompts to the hypothesis that keratinase is present in the units to break down keratins, structural proteins that form human skin scales, as sources of amino acids and ammonium to produce the odors. Seven bacterial species and four fungal species were identified in the units and room air. Airborne Staphylococcus haemolyticus and Methylobacterium organophilum counts contributed the most to the microbial dissimilarities of units with and without odor complaints. Keratinolytic bacteria and a methylotrophic bacterium were abundant in the units. All the units contained ammonium, and keratinase activity was higher in the units with odor complaints. Extracellular keratinase activity was more effective at 20 °C than at 30 or 4 °C. Keratinolytic bacteria produced high levels of ammonium in the culture with skin cells. Viable airborne microbial counts can help IAQ inspectors to identify potential odor-causing air-cooling units. Keratins may be broken down in the units and associated with the odor complaints.

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