MICROBIAL-GROWTH AND METABOLISM IN-HOUSE DUST

Microbial growth and production of carbon dioxide (CO2) and microbial volatile organic compounds (MVOC) were investigated in house dust. Acc ording to CO2 measurements, the metabolic activity increased after 11 days at 84-86% air relative humidity (RH) and after 3 days at 96-98% R H. Within 25 days, the concentration of fungal spores in house dust in creased to about 45-fold at 84-86% RH resulting mainly from the growth of Aspergillus, Eurotium and Penicillium. At 96-98% RH, the prolifera tions were on average 1370- and 240-fold for fungi and bacteria, respe ctively. The dominating fungal genera were Aspergillus and Penicillium . The MVOC composition revealed that microbes can utilize, for example , fatty acids and possibly aldehydes as carbon source resulting in the production of MVOC such as methyl ketones and alcohols. The main MVOC produced by microbes in house dust were 2-pentanone, 2-hexanone, 2-he ptanone, limonene, 2-methylfuran, formaldehyde, acrolein and nonanal. Also, 3-octanone, 2-ethyl-1-hexanol, 1-octen-3-ol, 3-methyl-1-butanol, 3-methyl-2-butanol, camphene and alpha-pinene can be considered to de rive from microbial metabolism to some extent. (C) 1997 Elsevier Scien ce Ltd. All rights reserved.