title: Submicronic fungal bioaerosols: high-resolution microscopic characterization and quantification.
abstract: Submicronic particles released from fungal cultures have been suggested to be additional sources of personal exposure in mold-contaminated buildings. In vitro generation of these particles has been studied with particle counters, eventually supplemented by autofluorescence, that recognize fragments by size and discriminate biotic from abiotic particles. However, the fungal origin of submicronic particles remains unclear. In this study, submicronic fungal particles derived from Aspergillus fumigatus, A. versicolor, and Penicillium chrysogenum cultures grown on agar and gypsum board were aerosolized and enumerated using field emission scanning electron microscopy (FESEM). A novel bioaerosol generator and a fungal spores source strength tester were compared at 12 and 20 liters min(-1) airflow. The overall median numbers of aerosolized submicronic particles were 2 × 10(5) cm(-2), 2.6 × 10(3) cm(-2), and 0.9 × 10(3) cm(-2) for A. fumigatus, A. versicolor, and P. chrysogenum, respectively. A. fumigatus released significantly (P < 0.001) more particles than A. versicolor and P. chrysogenum. The ratios of submicronic fragments to larger particles, regardless of media type, were 1:3, 5:1, and 1:2 for A. fumigatus, A. versicolor, and P. chrysogenum, respectively. Spore fragments identified by the presence of rodlets amounted to 13%, 2%, and 0% of the submicronic particles released from A. fumigatus, A. versicolor, and P. chrysogenum, respectively. Submicronic particles with and without rodlets were also aerosolized from cultures grown on cellophane-covered media, indirectly confirming their fungal origin. Both hyphae and conidia could fragment into submicronic particles and aerosolize in vitro. These findings further highlight the potential contribution of fungal fragments to personal fungal exposure.
authors.affiliation: National Institute of Occupational Health, Oslo, Norway.
authors.forename: Komlavi Anani
authors.initials: KA
authors.lastname: Afanou
authors.affiliation: National Institute of Occupational Health, Oslo, Norway.
authors.forename: Anne
authors.initials: A
authors.lastname: Straumfors
authors.affiliation: National Institute of Occupational Health, Oslo, Norway.
authors.forename: Asbjørn
authors.initials: A
authors.lastname: Skogstad
authors.affiliation: National Institute of Occupational Health, Oslo, Norway.
authors.forename: Terje
authors.initials: T
authors.lastname: Nilsen
authors.affiliation: National Institute of Occupational Health, Oslo, Norway.
authors.forename: Ole
authors.initials: O
authors.lastname: Synnes
authors.affiliation: Norwegian Veterinary Institute, Oslo, Norway.
authors.forename: Ida
authors.initials: I
authors.lastname: Skaar
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Science, Ås, Norway.
authors.forename: Linda
authors.initials: L
authors.lastname: Hjeljord
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Science, Ås, Norway.
authors.forename: Arne
authors.initials: A
authors.lastname: Tronsmo
authors.affiliation: Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA.
authors.forename: Brett James
authors.initials: BJ
authors.lastname: Green
authors.affiliation: National Institute of Occupational Health, Oslo, Norway wijnand.eduard@stami.no.
authors.forename: Wijnand
authors.initials: W
authors.lastname: Eduard
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D000391:Air Microbiology; D000392:Air Movements; D001232:Aspergillus fumigatus / Q000254:growth & development / Q000648:ultrastructure*; D008855:Microscopy, Electron, Scanning; D010408:Penicillium chrysogenum / Q000254:growth & development / Q000648:ultrastructure*; D013172:Spores, Fungal / Q000254:growth & development / Q000648:ultrastructure
chemical_list: D000336:Aerosols