Fungal and bacterial growth in floor dust at elevated relative humidity levels.
Under sustained, elevated building moisture conditions, bacterial and fungal growth occurs. The goal of this study was to characterize microbial growth in floor dust at variable equilibrium relative humidity (ERH) levels. Floor dust from one home was embedded in coupons cut from a worn medium-pile nylon carpet and incubated at 50%, 80%, 85%, 90%, 95%, and 100% ERH levels. Quantitative PCR and DNA sequencing of ribosomal DNA for bacteria and fungi were used to quantify growth and community shifts. Over a 1-wk period, fungal growth occurred above 80% ERH. Growth rates at 85% and 100% ERH were 1.1 × 104and 1.5 × 105spore equivalents d-1mg dust-1, respectively. Bacterial growth occurred only at 100% ERH after 1 wk (9.0 × 104genomes d-1mg dust-1). Growth resulted in significant changes in fungal (P<.00001) and bacterial community structure (P<.00001) at varying ERH levels. Comparisons between fungal taxa incubated at different ERH levels revealed more than 100 fungal and bacterial species that were attributable to elevated ERH. Resuspension modeling indicated that more than 50% of airborne microbes could originate from the resuspension of fungi grown at ERH levels of 85% and above.
Department of Civil, Environmental & Geodetic Engineering, College of Engineering, Ohio State University, Columbus, OH, USA.|Division of Environmental Health Sciences, College of Public Health, Ohio State University, Columbus, OH, USA.
K C
KC
Dannemiller
Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA.
C J
CJ
Weschler
Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA.
J
J
Peccia
D000391:Air Microbiology; D001419:Bacteria / Q000254:growth & development*; D004391:Dust / Q000032:analysis*; D005430:Floors and Floorcoverings; D005658:Fungi / Q000254:growth & development*; D006813:Humidity
D004391:Dust
DNA sequencing; bacteria; exposure; fungi; indoor microbiome; moisture; resuspension