A new field-compatible methodology for the collection and analysis of fungal fragments

A field-compatible collection system was developed and tested for the collection and analysis of fungal fragments. The new collection system consists of two types of Sharp-Cut cyclone samplers (PM2.5 and PM1.0) and an after-filter. Fungal particles are collected into three size fractions: (1) spores (> 2.5 mu m); (2) a fragment-spore mixture (1.0-2.5 mu m); and (3) submicrometer-sized fragments (< 1.0 mu m). The system was laboratory-tested using polystyrene latex (PSL) particles and particulate matter aerosolized from sporulating Aspergillus versicolor and Stachybotrys chartarum cultures. In addition to the particle count measured with direct-reading instruments, the (1 -> 3)-beta-D-glucan content in each size fraction was determined with the Limulus Amebocyte Lysate (LAL) assay. Experiments conducted with PSL particles showed that the50% cut-off values of the two cyclone samplers under the test conditions were 2.25 mu m and 1.05 mu m, respectively. No particle bounce onto the after-filter was observed when the total particle number entering the collection system was kept below 1.6 x 10(8). The ( 1 -> 3)-beta-D- glucan assay of samples aerosolized from both fungal species suggested that surface area is an important factor for determining the (1 -> 3)-beta-D-glucan content in the entire size-range of particles. In conclusion, the new methodology is a promising tool for separating and analyzing fungal fragment samples.