Ultraviolet radiation as a controlling and mutating agent of environmental fungi

Abstract

PurposeThe purpose of this paper is to study the effect of ultraviolet radiation (UVC) on the survivability and susceptibility of some fungal species isolated from the indoor air of agricultural, industry‐related workplaces.Design/methodology/approachEnvironmental fungi were collected from the air of cotton and soybean mills using liquid impinger sampler (AGI‐30). The UVC exposure experiment was performed on Aspergillus flavus, Aspergillus parasiticus, Aspergillus ochraceous, Aspergillus fumigatus, Aspergillus niger and Penicillium rubrum using UV lamp (λ=254 nm; 0.1 mW/cm2). The susceptibility constant (Z) was used to determine the susceptibility of any given organism to UVC.FindingsThe conidia survival was inversely proportional to the time of UVC exposure and ∼77‐88.5% of conidia were killed within six hours of exposure. Mutant conidia showed a wide range of morphological alterations including damage of their cell walls and features. Mycotoxin production patterns of the mutants Aspergillus flavus and Aspergillus parasiticus changed on comparison with the parental control patterns.Originality/valueThe paper provides information on the effect of UVC radiation on environmental fungi. The results reported in this research discussed the disadvantages of using UVC as a decontaminant of fungi.

Does Prolonged Exposure of Environmental Fungi to Ultraviolet Irradiation Change the Pattern of Drug Resistance?

“…Our findings are consistent with those of an earlier study performed by Abdel Hamee et al (16), who investigated environmental fungal samples obtained from the air of mills. They concluded that UV exposure could eradicate conidia and cause an inverse correlation between exposure duration and survival fraction of conidia (16). Pourkia et al (36) demonstrated that 8 h of UV irradiation was effective in reducing mycelium growth in comparison with that in the control samples on Pleurotus florida.…”

“…The pigmentation of cell walls with melanin also makes conidia less susceptible to UV damage (34,35). Our findings are consistent with those of an earlier study performed by Abdel Hamee et al (16), who investigated environmental fungal samples obtained from the air of mills. They concluded that UV exposure could eradicate conidia and cause an inverse correlation between exposure duration and survival fraction of conidia (16).…”

“…It seems that the inconsistency of our results with previous studies may be related to the shorter duration of UV irradiation. As previously reported by Abdel Hameed et al (16), some fungal agents may induce higher resistance to chemical and physical attacks after irradiation. Therefore, they may have a significant influence on pathogenesis.…”

“…exposed to various doses of UV lamp (power lamp 6W, Philips brand made in Poland; intensity: 0.8 mJ/cm 2 .s, length: 21.21 cm, lamp radiative power: 1.7 W, wavelength: 254 nm, distant between UV lamp and plates: 20 cm). The following formula was used to obtain the dose (16,21).…”

“…UV germicidal irradiation is a well-known method for inactivating a significant number of microorganisms and has wide application for sterilization. However, this method is accompanied by mutagenic effects, morphological changes, and different mycotoxin production patterns (16,17).…”