Preserved human remains from Militello Rosmarino (Sicily, 18th–19th centuries AD): assessing the microbial status of a late modern Italian mummy assemblage

Human mummies are an invaluable resource for bioarchaeology, providing insights into past diseases, behaviors, and funerary practices. However, their long-term preservation poses challenges, particularly when displayed publicly or stored in uncontrolled environments. This study seeks to assess the condition of an assemblage of spontaneously mummified religious dignitaries from Sicily, located in the recently reopened crypt of the mother church of Militello Rosmarino (province of Messina, Italy). Within the framework of the Sicily Mummy Project, we used the microbial community present on the remains as an indicator of both their condition and the environment in which they are stored. Samples were collected from the skin of 6 out of 41 individuals based on accessibility and overall preservation, yielding 54 isolates consisting of fungi and bacteria. Microorganisms were examined through cultivation, morphological characterization, biochemical tests, and molecular analyses such as RISA, 16S rDNA, and ITS1-5.8S-ITS2 rDNA sequencing. Hydrolytic activity assays revealed biodeterioration potential linked to cellulolytic and proteolytic microorganisms. Results showed that although the mummies had been neglected for a long time and covered in dust, they had been colonized by diverse cultivable fungi and bacteria with moderately harmful characteristics. The study emphasizes that, despite their predominantly environmental origin, the identified microorganisms could lead to both biodeterioration of the mummified remains and health risks for visitors. Therefore, appropriate cleaning and conservation interventions, along with constant monitoring of environmental parameters, are necessary to preserve this remarkable evidence of past funerary practices.