International Biodeterioration & Biodegradation 57 (2006) 163–167 Inactivation of fungi from deteriorated paper materials by radiation Manuela da Silva a,Ã , A.M.L. Moraes b , M.M. Nishikawa a , M.J.A. Gatti c , M.A. Vallim de Alencar d , L.E. Branda˜o d , A. No´brega c a Department of Microbiology, INCQS/Fundac - a˜o Oswaldo Cruz, 4365 Avenida Brasil, Manguinhos, Rio de Janeiro, RJ 21045-900, Brazil b Department of Mycology, Fundac - a˜o Oswaldo Cruz, 4365 Av. Brasil, CEP: 21040-900, Manguinhos c Department of Biology, IOC, Fundac - a˜o Oswaldo Cruz, 4365 Av. Brasil, CEP: 21040-900, Manguinhos d Department of Radioprotection/IEN/UFRJ, Cidade Universita´ria, Ilha do Funda˜o, Rio de Janeiro, RJ, Brazil Received 3 September 2005; accepted 7 February 2006 Available online 29 March 2006 Abstract Books and documents are subject to decay by a variety of organisms, including mould. Experiments were conducted to find the lowest gamma radiation dose needed to inactivate fungi. Aspergillus versicolor and Eurotium chevalieri, previously isolated from naturally contaminated book from a Brazilian public library and from the environment, respectively, were cultivated and treated in a Co 60 irradiation unit with doses ranging from 14.5 to 25 kGy. The minimum dose required to kill these fungi was 16 kGy. Thus, this dose was applied directly to a severely attacked book and deteriorated old documents. Pieces of damaged paper from these materials were incubated in culture media before and after the treatment. Several fungi were isolated and identified, including representatives of Acremonium, Aspergillus, Cladosporium, Fusarium, Penicillium and Trichosporon. After the treatment, no living fungi were detected from the irradiated material. The book was maintained in favorable conditions for new fungal attack for 2 months and no fungal growth was detected. These results are very promising and demonstrate the effectiveness of gamma-ray radiation for the recovery of severely damaged books and old documents, leading to the preservation of our cultural heritage and prevention of diseases caused by moulds in libraries and archives. r 2006 Elsevier Ltd. All rights reserved. Keywords: Fungi; Gamma radiation; Preservation; Books; Documents 1. Introduction Libraries and archives sometimes have suitable condi- tions for fungal growth, which is highly dependent of temperature and humidity. Tropical countries, like Brazil, where high humidity and temperature are frequent, have environmental conditions that encourage the development of these microorganisms. This situation can bring risks to human health by mould contamination of books and documents, besides causing the decay of these publications, which sometimes are antique and rare (Gonzalez et al., 2002). Libraries and museums are responsible for preser- ving our heritage; they have the challenge to preserve millions of books printed on fragile paper manufactured through processes from the 19th century (Egan et al., 1995). Fungi can hydrolyse a wide variety of polymers, including cellulose, as a result of their efficient degradative enzymes (Bennett and Faison, 1997). Cellulolytic fungi, which use cellulose as substratum, when growing in favorable environmental conditions, can destroy paper material in a short time (Adamo et al., 2003). Several techniques have been developed for book and document conservation reducing the threat of biodeteriorating agents, such as fungi. Some of these techniques involve the use of very toxic chemicals, including ethylene oxide, which has carcinogenic properties and is banned in a number of countries, besides being expensive (Flieder et al., 1994; Adamo et al., 2001; Gonzalez et al., 2002). An alternative is the use of gamma-ray radiation, a promising treatment in the preservation field. ARTICLE IN PRESS www.elsevier.com/locate/ibiod 0964-8305/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ibiod.2006.02.003 Ã Corresponding author. Tel.: +55 21 3865 5186; fax: +55 21 2290 0915. E-mail address: manuela@incqs.fiocruz.br (M. da Silva).