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Huge numbers of cultural objects were damaged by microorganisms after having been soaked with seawater from the tsunami that followed the Great East Japan Earthquake on March 11, 2011. Among the cultural objects that were damaged, paper-based objects in the tsunami area were severely affected. In the present study, a culture-based analysis and on-site investigations were carried out to determine the extent of the microbial deterioration of paper-based objects (i.e., administrative documents and historical documents). Dark-colored fungi were isolated from black-spotted paper as Stachybotrys chartarum , which was observed to grow significantly in mineral salt medium supplemented with cellulose as the sole nutrient source; growth was shown in 10% NaCl. Two isolates from light red-spotted paper were related to Streptomyces sp. and Myxotrichum sp., respectively. These isolates generated red pigments in the mycelia and on the culture plates. Penicillium -related isolates were dominant in the sample tested, and they showed a higher level of NaCl tolerance. From the results of our on-site investigations, a unique discoloration, mainly black- and light red-spotted alterations caused by microbes, was observed on many paper-based objects that had been left wet for several months. The adhesive tape method applied to the black-spotted and red-spotted areas on damaged documents, Stachybotrys , Chaetomium and Cladosporium , and Actinomycetales bacterium were observed, respectively. With regard to the discoloration found on tsunami-affected paper-based objects, Stachybotrys and Streptomyces sp. seem to be responsible for the black- and red-spotted paper alterations, respectively.

An International Symposium on the Conservation and Restoration of Cultural Property with a focus on microbial biodeterioration of cultural property was held in Tokyo, Japan on December 5–7, 2012. In addition to microbial deterioration of stone, paper and wood, available technologies and innovations in removal and protection of cultural property, monitoring fungal contamination and classification of the contamination level, this symposium showed results dealing with cultural property after earthquake and tsunami as the key issues affecting the artifacts and cultural property highlighted at this symposium. Interestingly, it was found that salt in water can control the growth of molds and fungi on documents and less growth was observed when salinity was higher. This has a greater implication when dealing with large amounts of documents after natural disaster. The papers derived from invited speakers and also posters are being published in a dedicated volume of book available to research scientists, conservationists, applied biologists and graduate students working on related subjects.