Current Research

The quantity, identity, and distribution of biomass in indoor and outdoor aerosols are poorly described. This is not consistent with the current understanding of atmospheric chemistry or the microbiological characterization of aquatic and terrestrial environments. This knowledge gap is due to both difficulties in applying contemporary microbiological techniques to the low biomass concentrations present in aerosols, and the traditional reliance of aerosol researchers on culture-based techniques—the quantitative limitations and ecological biases of which have been well-documented and are now avoided in other environmental matrices. Our research in this area is focuse on the effects of environmetnal change and pollution on the potentcy of allergens and fundamental studies to determine contribution of human occupation, dust resuspension, and out door air to the sources of biological material in indoor air.

Effect of environment (Temperature) on the potency of allergens:

     Type I hypersensitivity reactions including allergic asthma and allergic rhinitis are a major cause of illness and disability in the U.S. Up to 40% of the members of the general public have developed IgE antibodies against environmental antigens, and 20% demonstrate upper respiratory symptoms typical of rhinitis1. Both the presence of IgE and exposure to airborne allergens are strong risk factors for asthma. Allergic asthma, where allergens trigger attacks in 60% to 90% of asthmatic children and 50% of asthmatic adults is the most common form of asthma. Allergies and exacerbation of asthma are strongly linked to allergen exposure and the environments in which this exposure occurs. Whole organisms that are known allergens, including fungi and pollen, typically contain multiple protein allergenic epitopes. Interaction between the environment and these organisms suggests that conditions including temperature and air pollutant type may significantly change the potency of these allergens and thus strongly affect allergen exposure in asthmatics. We hypothesize that temperature affect fungal allergenicity through the regulation of gene expression during growth or by post translational modifications of allergenic proteins.

     Accordingly, recent results from out lab have demonstrated a dramatic change in per spore allergenicity as a function of growth temperature in the fungi Aspergillus fumigatus. Depending on the original growth temperature, the potency of an indivitual allergen spore may vary by over 100 times for a 10C change in growth temperature. Preliminary expression microarray results at these temperatures have revealed that genes coding for 13 of the 23 known A. fumigatus allergens are over expressed at temperatures below 17ºC.

Sources and origins of biologial matierial indoors

     Many aspects of biological aerosol behavior, such as transport, deposition, and resuspension, can be described by physical indoor air quality models. Indoor environments, however, exhibit broad ranges in microbial species distribution and diversity of phenotypic potential. Addressing these aerosol dynamics requires a molecular-biology tool kit as well as a microbial ecology framework that seeks to understand quantity and identity of microorganisms.The goal of our indoor air research is to integrate the study of physical aerosol processes with molecular biology-based tools to describe the dynamics and sources (indcluding human) of biological aerosols in indoor environments. The focus on aerosols reflects the dominant human exposure route and facilitates examination of indoor surface-bound microbial material through resuspension processes. Three research objectives are proposed. The first catalogs the particle size distributions for a variety of biological aerosol types in buildings under occupied and unoccupied conditions. The second objective seeks to apply these models to describe quantitatively the significance of specific and total outdoor and indoor sources on the microbial content of indoor biological aerosols. The final objective will then generate phylogenetic libraries and apply aerosol receptor modeling to determine the origin (original source such as crustal material, growth, fecal matter, etc.) of the biological material in the indoor environment. Overall, our approach is designed to set a strong foundation for researchers to build upon for advancing microbial science and ecology in indoor environments.