Development of a high-volume aerosol collection system for the identification of air-borne micro-organisms

Aims: A high-volume aerosol collector was developed to efficiently capture airborne bacteria in order to assess levels of diversity in the air. Methods and Results: Particulate matter was collected on a device designed to filter 1.4 x 10(6) litres of air in a 24 h period on a 1-mum pore size polyester membrane. Methods were optimized for extraction of genomic DNA from the air filter concentrate. Preparation times of 90 s with 0-5-0-05 mm diameter zirconia/silica beads yielded the highest concentration genomic DNA that was able to support PCR. A 24-h air sample was taken in Salt Lake City, Utah and the microbial composition was determined by the amplification and sequence analysis of 16S ribosomal DNA fragments. Conclusions: Sequence analysis revealed a large diversity in the type of microbial species present including clones matching the sequence of Clostridium botulinum. The primary components of the aerosol sample included many different spore-forming bacteria as well as more fragile members of the Proteobacteria division. Significance and Impact of the Study: The high-volume air collection and genomic DNA recovery system allows for the rapid detection of both cultivable as well as culture-resistant organisms in the environment.