title: Release and characteristics of fungal fragments in various conditions.
abstract: Intact spores and submicrometer size fragments are released from moldy building materials during growth and sporulation. It is unclear whether all fragments originate from fungal growth or if small pieces of building materials are also aerosolized as a result of microbial decomposition. In addition, particles may be formed through nucleation from secondary metabolites of fungi, such as microbial volatile organic compounds (MVOCs). In this study, we used the elemental composition of particles to characterize the origin of submicrometer fragments released from materials contaminated by fungi. Particles from three fungal species (Aspergillus versicolor, Cladosporium cladosporioides and Penicillium brevicompactum), grown on agar, wood and gypsum board were aerosolized using the Fungal Spore Source Strength Tester (FSSST) at three air velocities (5, 16 and 27 m/s). Released spores (optical size, dp ≥ 0.8 μm) and fragments (dp ≤ 0.8 μm) were counted using direct-reading optical aerosol instruments. Particles were also collected on filters, and their morphology and elemental composition analyzed using scanning electron microscopes (SEMs) coupled with an Energy-Dispersive X-ray spectroscopy (EDX). Among the studied factors, air velocity resulted in the most consistent trends in the release of fungal particles. Total concentrations of both fragments and spores increased with an increase in air velocity for all species whereas fragment-spore (F/S) ratios decreased. EDX analysis showed common elements, such as C, O, Mg and Ca, for blank material samples and fungal growth. However, N and P were exclusive to the fungal growth, and therefore were used to differentiate biological fragments from non-biological ones. Our results indicated that majority of fragments contained N and P. Because we observed increased release of fragments with increased air velocities, nucleation of MVOCs was likely not a relevant process in the formation of fungal fragments. Based on elemental composition, most fragments originated from fungi, but also fragments from growth material were detected.
authors.affiliation: Department of Environmental Science, University of Eastern Finland, Yliopistonranta 1D, P. O. Box 1627, FI-70211 Kuopio, Finland.
authors.forename: Jacob
authors.initials: J
authors.lastname: Mensah-Attipoe
authors.affiliation: Department of Physics, Tampere University of Technology, Korkeakoulunkatu 3, 33720 Tampere, Finland.
authors.forename: Sampo
authors.initials: S
authors.lastname: Saari
authors.affiliation: Department of Environmental Science, University of Eastern Finland, Yliopistonranta 1D, P. O. Box 1627, FI-70211 Kuopio, Finland.
authors.forename: Anna-Maria
authors.initials: AM
authors.lastname: Veijalainen
authors.affiliation: Department of Environmental Science, University of Eastern Finland, Yliopistonranta 1D, P. O. Box 1627, FI-70211 Kuopio, Finland.
authors.forename: Pertti
authors.initials: P
authors.lastname: Pasanen
authors.affiliation: Department of Physics, Tampere University of Technology, Korkeakoulunkatu 3, 33720 Tampere, Finland.
authors.forename: Jorma
authors.initials: J
authors.lastname: Keskinen
authors.affiliation: SIB Labs, University of Eastern Finland, Yliopistonranta 1E, P. O. Box 1627, FI-70211, Kuopio, Finland.
authors.forename: Jari T T
authors.initials: JTT
authors.lastname: Leskinen
authors.affiliation: Department of Environmental Science, University of Eastern Finland, Yliopistonranta 1D, P. O. Box 1627, FI-70211 Kuopio, Finland; Department of Environmental Health, University of Cincinnati, P.O. Box 670056, Cincinnati, OH 45267-0056, USA. Electronic address: reponeta@ucmail.uc.edu.
authors.forename: Tiina
authors.initials: T
authors.lastname: Reponen
mesh_terms: D000391:Air Microbiology; D016902:Air Pollution, Indoor / Q000032:analysis*; D003252:Construction Materials / Q000382:microbiology; D004784:Environmental Monitoring; D005658:Fungi; D013172:Spores, Fungal
keywords: Air velocity; Elemental analysis; Energy Dispersive X-ray spectroscopy; Fragments; Scanning electron microscope