Fungicidal effects of ultraviolet light (254 nm) irradiation on contaminated museum packing and storing materials

Abstract

In storage of modern museums, collections are packed and stored with acid-free paper-based materials for keeping safe and stable conditions. Direct contact of fungal contaminated packing and storing materials with the collections is concerned about expanding of infection in storage facilities. In this study, fungicidal effects of UV light irradiation on the materials such as archival board and Japanese tissue paper contaminated with Penicilliun commune and Chaetomium globosum were tested. The analyzed materials were divided into two groups; Group 1 was examined with 20 ul of spore suspensions of fungi (10 6 cfu/ml); and Group 2 was tested on Czapek-Dox agar medium modified without sugar and inoculated with 100 ul of the spore suspensions of fungi (10 6 cfu/ml). Six doses of UV irradiation were examined on Group 1 and five doses on Group 2 in addition to control. The assessment was done by using 1) adenosine triphosphate (ATP) bioluminescence assay and double staining to determine the cell viability; 2) observation under light microscope to evaluate morphophysiological change of tested fungi (spores and hyphae). Because of the thinness and high transparency of tissue paper, UV irradiations were highly efficient to fungicide its fungal contamination compared with archival board. In spite of the high resistance of C. globosum spores, the rate of growth was slow, and with a little amount of perithecia or fruiting bodies and a high amount of mycelium (which damaged rapidly through UV irradiation). This may be due to a low relative humidity of the incubation environment. Minimum dosage of UV irradiation with fungicidal effectiveness against all fungal contamination was estimated as 118 J/cm 2 .