Microscopic and qPCR comparison of fungal growth in residential carpets with different carpet fiber materials, at varying relative humidity levels, and presence of household dust
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Date
2018-12
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The Ohio State University
Abstract
People spend 90% of their time indoors exposed to the microbiome of the built environment. Fungal species are part of this indoor microbiome that have been found to grow on various components of residential homes including house dust, wallpaper, gypsum, insulations, and carpet. Fungal fragments resuspended from carpets are a significant source of human exposure and emissions from metabolic processes can have adverse health effects, such as allergies and exacerbation of asthmatic symptoms. Understanding the process and resulting morphology of fungal growth on residential carpet can provide valuable insights for creating indoor environmental conditions that can improve quality of life for sensitive groups. The goal of this study was to compare fungal growth morphology in residential carpet in varying environmental conditions including relative humidity (RH), carpet fiber material, and the presence/absence of house dust. RH conditions were simulated using three carpet and dust samples extracted from homes in Ohio. Wool, olefin, and nylon carpet fibers were also tested using no dust, sterilized dust, and non-sterile house dust spiked with Aspergillus versicolor and Alternaria alternata spores obtained from ATCC. Morphology was observed using scanning electron microscopy and confocal microscopy. Fungi were resolved utilizing Uvitex 2B fluorescent stain. qPCR was used to quantify fungal growth in the conditions tested. The presence of house dust was determined to be the most important variable that increased fungal growth. Elevated RH (>90%) and natural carpet fibers compared to synthetic were also factors that increased fungal growth in carpets. The results of this study can provide valuable insights for care providers to look for in patient’s homes, motivating improved cleaning practices to remove dust, and guide future building designs to mitigate human exposure to fungi in the built environment. In addition, these results show that synthetic carpet fibers can minimize the growth and proliferation of fungi.
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Keywords
Built Environment, Indoor Air, Fungi, Microbiology, Environmental Engineering