Determining the Growth and Vitality of Micro-Organisms in Carpets and Mattresses in Non-Problem Dwellings by Measuring CO2 Released during Respiration

Abstract

Bedroom carpets and mattresses devoid of any reported or observed moisture damage or problems were ana lysed as sources of indoor fungal growth by determining the amount of CO₂ released from respiration by micro organisms living in furnishings. Dust was extracted from the carpets and mattresses using a Kirby G5 vacuum cleaner. The basal respiration rate of the dust samples without moisture added was used to estimate base respi ration rate and a substrate-induced respiration rate method was used to estimate the vitality of micro-organ isms in the dust and to estimate the amount of living microbial biomass. Analysis of fungal species was per formed by direct sprinkling of dust samples and stamp ing the filter collection papers directly onto a range of nutrient agars. Fungal differentiation revealed 18 species were living in the carpets and 12 species in the mat tresses. Penicillium spp., Aspergillus niger and Zygomy cetes were dominant fungi. The relative abundances of fungal species in the carpets were significantly corre lated to the species in the mattresses. The basal CO₂ res piration rate and the living microbial biomass from all samples was the same as several soil types including sandy loam soils, Para Brown Earth, Sandy Brown Earth and Brown Podzol. The rate of respiration showed that the fungal species detected were living in the furnish ings, and were highly metabolically active. This revealed that bedroom carpets and mattresses in non-problem dwellings and without moisture damage can provide a habitat with enough moisture to support fungal growth despite the lack of an obvious moisture source.