Skin squames contribute to ammonia and volatile fatty acid production from bacteria colonizing in air-cooling units with odor complaints

Abstract

One of the most notable Indoor Air Quality problems is odor emission. This study investigated the potential contribution of skin squames to the production of ammonia (NH ) and volatile organic acids (VFAs) by 7 bacteria isolated from air-cooling (AC) units with complaints of urine and body odors. Our previous study showed that keratinolytic activity is higher in AC units with odor complaints than those without. In the offices where these units are located, the most likely source of keratins is from human skin squames. Most bacteria can produce NH and VFAs in the skin squame culture. Some correlations between the levels of NH , NH4+, VFAs, and keratinolytic activity were found. The odor production pathway with skin squames was proposed. Staphylococcus haemolyticus was abundant in the AC units with odor problems and had a high level of keratinolytic activity in addition to odor production. For long-term odor control, it is important to reduce the level of skin squames entering the AC units.

Building upon current knowledge and techniques of indoor microbiology to construct the next era of theory into microorganisms, health, and the built environment

“…Moreover, there are plenty of nutrient substrates. Human skin squamous cells shed indoors serve as a ready food source for bacteria living in HVAC systems [93], and sufficient nutrients exist in house dust to host a living bacterial community even after 90 days of isolation [85].…”

From one species to another: A review on the interaction between chemistry and microbiology in relation to cleaning in the built environment

“…Yet "green" is an inexact term and regulation has not always kept pace with marketing; "green" products thus far do not inherently exhibit lower emission rates of all, or even some, classified hazardous VOCs, despite consumer perceptions. Microorganisms can subsist off organic material found in dust, especially sloughed human cells, 24,25 and their production of ammonia and volatile fatty acids can be sufficient to spur odor complaints. 16,17 Once leached into and incorporated into dust, chemicals can be resuspended into indoor air by occupant traffic, airflow from ventilation, and routine cleaning activities, allowing these chemical species to be inhaled, ingested, or otherwise come into contact with human skin.…”

“…10,13,15 Semi-volatile organic compounds (SVOCs), a subcategory of VOCs with a higher molecular weight, are commonly incorporated into materials in the built environment for a variety of purposes and can also be found in detergents ( Figure 1); but these, too, may leach and accumulate in dust on surfaces. 25 However, low MVOC production, the plurality of microbial and chemical sources of chemicals indoors, and instrument detection limits can make it difficult to accurately classify a chemical as an MVOC. [18][19][20][21] Collectively, the chemicals present in cleaning solutions, as well as the reactions caused by solutions interacting with surfaces, can cause negative health effects in building occupants, especially those with close or frequent contact to the products.…”

“…26,34 However, these correlations are always not statistically significant, 34 suggesting a more intricate relationship between individual MVOCs and health, or a limitation of using self-reported symptoms. 27 Collectively, MVOCs, microbial metabolites, and building-sourced VOCs apparently affect indoor chemistry, human health, and well-being, 25,34,36 and the generalization of poor indoor air quality and resulting negative effects on occupants are known as sick building syndrome. 35 MVOCs produced by fungi, in particular, may be poorly characterized, and it has been hypothesized that many of these MVOCs could also be classified as mycotoxins.…”

“…14,[21][22][23] Similarly, microorganisms can either process VOCs to create microbial volatile organic compounds (MVOCs) or independently produce MVOCs (Figure 1). Microorganisms can subsist off organic material found in dust, especially sloughed human cells, 24,25 and their production of ammonia and volatile fatty acids can be sufficient to spur odor complaints. 25 However, low MVOC production, the plurality of microbial and chemical sources of chemicals indoors, and instrument detection limits can make it difficult to accurately classify a chemical as an MVOC.…”