Please cite this article in press as: A. DeAraujo, et al., Investigation of the recent microbial degradation of the skin of the Chinchorro mummies of Ancient Chile, Journal of Cultural Heritage (2016), http://dx.doi.org/10.1016/j.culher.2015.11.004 ARTICLE IN PRESS G Model CULHER-3009; No. of Pages 7 Journal of Cultural Heritage xxx (2016) xxx–xxx Available online at ScienceDirect www.sciencedirect.com Original article Investigation of the recent microbial degradation of the skin of the Chinchorro mummies of Ancient Chile Alice DeAraujo a,∗ , Archana Vasanthakumar a,1 , Marcela Sepulveda b,2 , Vivien Standen c,3 , Bernardo Arriaza d,4 , Ralph Mitchell a,5 a Laboratory of Applied Microbiology, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States b Universidad de Tarapacá, Laboratorio de Análisis e Investigaciones Arqueométricas, Instituto de Alta Investigación, Arica, Chile c Universidad de Tarapacá, Departamento de Antropología, Arica, Chile d Universidad de Tarapacá, Instituto de Alta Investigación, Arica, Chile a r t i c l e i n f o Article history: Received 11 May 2015 Accepted 9 November 2015 Available online xxx Keywords: Mummies Microorganisms Skin Biodegradation Keratinolytic Collagenolytic a b s t r a c t Biodeterioration of cultural heritage artifacts due to microbial activity presents a significant challenge to conservators and museums around the World. A collection of Chinchorro mummies recovered from the Atacama Desert (the oldest artificial mummies ever found, dating back to 5050 B.C.E.) has been stored in the Universidad de Tarapacá, northern Chile. Over the past ten years, accelerated deterioration of some mummies has been documented. Blackening and exudation of some areas of their remaining skin is causing disfigurement of the mummies and poses a threat to the collection, also for mummies in situ exposed to the natural environment. This study was designed to provide a broad analysis of the skin microbiota of Chinchorro mummies and, investigate the relationship between the presence of microbes and the recent discoloration and biodegradation of the Chinchorro mummies’ skin. Microorganisms iso- lated from degraded Chinchorro mummy skin samples were similar, based on ribosomal RNA analysis, to bacteria found in the human skin microbiome (predominantly, Bacillus, Staphylococcus, and Methy- lococcus spp.) and commonly occurring fungi (predominantly, Penicillium and Aspergillus spp.). Some of these microorganisms were able to utilize collagen and/or keratin as the sole carbon source in vitro. We determined the activity of the collagenase/gelatinase enzymes produced by these microorganisms when grown on pig skin, which was used as a surrogate for human skin. The concentration of hydroxyproline, a measure of collagenous protein degradation by the microorganisms, increased with increasing relative humidity. We demonstrated that keratinolytic and collagenolytic opportunistic microorganisms were likely responsible for the recent degradation phenomenon. © 2015 Elsevier Masson SAS. All rights reserved. ∗ Corresponding author. 58, Oxford Street, Room 301, Cambridge MA 02138, United States. Tel.: +1 617 495 4180; fax: +1 617 496 1471. E-mail addresses: alice.usa@hotmail.com (A. DeAraujo), archanav@seas.harvard.edu (A. Vasanthakumar), marcelaasre@gmail.com, msepulveda@uta.cl (M. Sepulveda), vivien.standen@gmail.com (V. Standen), barriaza@uta.cl (B. Arriaza), mitchell@seas.harvard.edu (R. Mitchell). 1 Address: 58, Oxford Street, Room 301, Cambridge MA 02138. Tel.: +1 617 495 3307; fax: +1 617 496 1471. 2 Address: Antofagasta 1520, Arica, Chili. Tel.: +56 58 2230304. 3 Address: 18 de Septiembre 2222, Casilla 6D, Arica, Chili. Tel.: +56 58 2205551. 4 Address: Antofagasta 1520, Arica, Chili. 5 Address: 29, Oxford Street, Room 126, Cambridge MA 02138. Tel.: +1 617 496 3906. 1. Research aims A collection of Chinchorro mummies (the oldest artificial mummies ever found, dating back to 5050 B.C.E.) is being stored in the museum at Universidad de Tarapacá, in Arica, the north- ernmost region of Chile. In the last decade, a blackening and oozing of mummy skin have been documented. This degrada- tion has coincided with increases in humidity, leading to the hypothesis that climate and/or environmental change could have brought about alterations in the skin environment, thereby mak- ing the skin more susceptible to degradation. The objective of this new study was three-fold: to investigate the role of microor- ganisms in the discoloration of the Chinchorro mummy skin, to study the biochemical processes underlying biodeterioration, and to investigate the changes in environmental conditions that precip- itate biodeterioration of the Chinchorro mummies’ skin. The data obtained in this study will facilitate the development of methods to http://dx.doi.org/10.1016/j.culher.2015.11.004 1296-2074/© 2015 Elsevier Masson SAS. All rights reserved.