Microbial biodeterioration of human skeletal material from Tell Leilan, Syria (2900 – 1900 BCE)

Abstract

Human bone is considered one of the most direct and insightful sources of information on peoples of the past. As a result, curation protocols have been developed to ensure that the integrity of human skeletal collections is maintained. Although collections are generally considered safe when these protocols are followed, the results of this investigation show that the Tell Leilan skeletal collection from Syria (circa 2900 – 1900 BCE) was contaminated by microbial growth (also known as biodeterioration) during curation. This biodeterioration was evaluated by light microscopy (LM), by the application of a histological preservation index (HPI), and by scanning electron microscopy (SEM). All samples (n=192) were found to be biodeteriorated by LM and the HPI. SEM confirmed that the Tell Leilan skeletal material had been contaminated by a complex microbial aggregate known as a biofilm. Amycolatopsis sp. and Penicillium chrysogenum, along with species of Aspergillus, Chaetomium, and Cladosporium were isolated and cultured from several contaminated bones and were identified based on morphology and DNA sequences. The results of this research suggest that we must focus on new techniques to examine bone as well as on new conservation protocols designed to limit the growth of biofilms in human skeletal collections in the future.