Reconstructing skin microbiome of G. Clemenceau (1929): paleoproteomic analysis of his bath sponge.

Paleoproteomic analysis of a bath sponge belonging to Georges Clemenceau explores the possibility of reconstructing the skin microbiome of a historical figure from a preserved personal item. Using high-resolution mass spectrometry and a cascade proteotyping strategy, several microorganisms were identified, dominated by environmental bacteria of the genus Pseudomonas and opportunistic fungi such as Aspergillus and Exophiala. Traces of Escherichia coli, human proteins, marine organisms, and plants were also detected. Overall, the results suggest that the sponge does not accurately reflect Clemenceau's stable skin microbiome, as microorganisms typically associated with human skin are absent, likely due to taphonomic biases and preservation phenomena. On the contrary, the object appears as a complex microenvironment that has accumulated contamination over time related to humidity, the domestic and coastal environment, as well as the conditions of use and storage. The presence of opportunistic microorganisms, notably Exophiala sideris, even suggests a potential risk of skin infections in an elderly diabetic individual. This study thus demonstrates that everyday objects can constitute unique biological archives for paleopathology, not for precisely reconstructing an individual microbiota, but for documenting dermatological hygiene practices, microbial environments, and the infectious risks associated with reusable, damp objects at the beginning of the 20th century.