205 The Bacteriological Contamination of Archaeological Ceramics: an Example from Pachacamac (Peru) Kusi Colonna-Preti*, Peter Eeckhout Keywords ceramics; archaeological objects; bacteria; biodeterioration; biocide Abstract This paper concerns the efflorescence of bacteria on ceramics from archaeological excavations. Biodegradation was due to Streptomyces Sp., a bacterium of the Actinomycetale order. After analysis of each contaminated object, its location in the storeroom, and our conservation materials, it is suggested that the origin of the bacteria is in the soil of the archaeological site. Microclimatic conditions and organic nutrients from the soil create a favourable atmosphere for the development of bacteria inside the storeroom. With regard to conservation treatment, the desalination process does not prevent the emergence of bacteria but appears to restrict it considerably. The application of the biocide Biotin R at 2%, diluted in ethanol, has been successful: there has been no recurrence of the bacteria. Fig. 1. Excavations of Cemetery 1 at Pachacamac (Photo: P. Eeckhout).