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The effect of sunlight on allergen release from spores of the fungus Alternaria
Teresa Z Mitakakis A1, Timothy J O'meara A2, Euan R Tovey A2
A1 Cooperative Research Centre for Water Quality and Treatment, Infectious Disease Epidemiology Unit, Department of Epidemiology and Preventive Medicine, Faculty of Medicine, C & EMS, Campus Clayton Monash University, 3rd Floor 553 St. Kilda Road Melbourne VIC 3004 Australia
A2 Institute of Respiratory Medicine, Department of Medicine The Royal Prince Alfred Hospital/The University of Sydney Room 461, Blackburn Bldg (D06), Camperdown Sydney NSW 2006 Australia Teresa.Mitakakis@med.monash.edu.au
Abstract:
Airborne fungal spores are known carriers of allergen. Correlations between spore counts and allergen concentrations are poor. It is known that germination increases allergen release, implicating spore viability as a determinant of allergen release. During aerial dispersal, spores can be exposed to prolonged periods of ultraviolet (UV) light which can reduce viability of spores. We examined the relation between spore viability and allergen release in two experiments: firstly spores from culture were treated with a UV wavelength of 254 nm (not present in sunlight reaching the earth's surface) or autoclaved, and secondly, spores were exposed to simulated sunlight over three days. In both studies viability was measured (by germination on agar and by metabolic activity with nitro-blue tetrazolium vital stain) and allergen release by the Halogen immunoassay. The UV light reduced the proportion of spores able to germinate but did not affect metabolic activity or allergen release. Autoclaving reduced the proportion of spores releasing allergen by half (p<0.0001). Three days' exposure to simulated sunlight correlated negatively with spore germination and metabolic activity (p<0.0001), but did not affect allergen release (p=0.799). In conclusion, simulated sunlight reduced the metabolic activity and germinability of spores however the proportion releasing allergen remained unaffected. These findings suggest that spore counts may reflect allergen concentrations in the air if spores are dead or dormant. The contribution of viable spores to concentrations of airborne allergen, as well as the role of germination in allergen delivery to the respiratory tract, remains to be resolved.
Life Sci Space Res. 1979;17:105-10.
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Imshenetsky AA, Lysenko SV, Lach SP.
Institute of Microbiology, USSR Academy of Sciences, Moscow, USSR.
Of the six species of microorganisms isolated from the mesosphere, five contained pigments and were more resistant to UV radiation compared with their pigment-free mutants. The black pigment isolated from the conidia of Aspergillus niger considerably increased the UV resistance of the unpigmented mutant conidia of Penicillium notatum, the spore Circinella muscae and the vegetative cells of Micrococcus albus. From the data it is possible to conclude that in the upper layers of the Earth's atmosphere the predominant proportion of pigmented microorganisms is the consequence of natural selection by UV radiation.
Study of microbial resistance to ultraviolet radiation.
Gola, S
IND. CONSERV. Vol. 57, no. 1, pp. 26-29. 1982.
Several bacteria and fungi, suspended in distilled water and in saline, were irradiated with a 15-W u.v. lamp which had a radiation intensity of 6 mW/cm super(2) at 5 centimeters' distance. The u.v. resistance of the microorganisms tested was found to increase in the order bacterial vegetative cell < yeasts < bacterial spores < fungal spores. With this lamp, a great sporicidal effect was observed in irradiation times about 20-fold shorter than those required with the other lamp. Survival curves were not exponential. Survival rate was found to depend on the initial concentration of spores, the sporicidal effect decreasing with decreasing initial number of spores. The use of the UV-C-13 lamp, though very effective, did not allow complete inactivation of fungal spores suspended in distilled water to be obtained in relatively short times.
Descriptors: microorganisms; U.V. radiation; fungi; bacteria; Bacillus pumilus; Bacillus stearothermophilus; Clostridium sporogenes; Escherichia coli; Micrococcus; Serratia marcescens; Salmonella typhimurium; Candida albicans; Saccharomyces cerevisiae; Aspergillus; Penicillium; Bacillus cereus |
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