Resistance of airborne fungal propagules to ultraviolet irradiation: Laboratory study

Abstract

The influence of ultraviolet (UV) radiation on fungi Aspergillus niger Tiegh. isolate OG168, Paecilomyces puntonii (Vuill.) Nann. isolate OG68, and Penicillium expansum Link isolate PO88 was studied under laboratory conditions. A test system was developed for this study. An aerosol chamber provided a dust-free space of 1.5 m³. The source of ultraviolet rays was an UV lamp (DPT 220, 240–320 nm, 15 W). Fungal propagules were injected into the UV exposed chamber space from an external bioaerosol generator. Aerosols from the aerosol chamber after irradiation to UV were sampled into an impinger AGI-30 and measured with the optical aerosol spectrometer LAS-15M (Institute of Physics, Lithuania). The changes in fungi survival caused by exposure to UV radiation were evaluated by determining their relative recovery. The laboratory study indicated that the fungal propagules responded to UV radiation distinctively. P. puntonii propagules were injured without possibility to repair. On the contrary, P. expansum propagules repaired after a long enough exposure to UV radiation, but this ability was limited. The stressed A. niger propagules recovered after the 80 min exposure to UV radiation and the relative recovery reached a plateau. The mutagenic effects of UV light on tested fungi have shown that frequent occurrence of different morphological mutants was detected after the 30 min exposure of conidia. The mean geometrical diameter of fungal propagules exposed to UV irradiation in the aerosol chamber was in the range of 2.5 to 2.8 μm.
Keywords: aerosol chamber, fungal propagules, relative recovery, mutation, UV radiation
PACS: 92.60.Mt, 92.20.Bk, 87.19.xg