Proteomic Analyses on an Ancient Egyptian Cheese and Biomolecular Evidence of Brucellosis

The material analyzed in this study is probably the most ancient archeological solid residue of cheese ever found to date. The sample was collected during the Saqqara Cairo University excavations in the tomb of Ptahmes dated to XIX dynasty (El-Aguizy, O. Bulletin de l'Institut Francaise d'Archeologie Orientale (BIFAO) 2010, 110, 13-34 (ref 1); Staring, N. Bulletin de Institut Francais d'Archeologie Orientale (BIFAO) 2015, 114, 455-518 (ref 2)). Our biomolecular proteomic characterization of this archeological sample shows that the constituting material was a dairy product obtained by mixing sheep/goat and cow milk. The interactions for thousands of years with the strong alkaline environment of the incorporating soil rich in sodium carbonate and the desertic conditions did not prevent the identification of specific peptide markers which showed high stability under these stressing conditions. Moreover, the presence of Brucella melitensis has been attested by specific peptide providing a reasonable direct biomolecular evidence of the presence of this infection in the Ramesside period for which only indirect paleopathological evidence has been so far provided (Pappas, G.; Papadimitriou P. Int. J. Antimicrob. Agents 2007, 30, 29-31 (ref 3); Bourke, J. B. Medical History 1971, 15 (4), 363-37S (ref 4)). Finally, it is worth noting that, although proteomic approaches are successfully and regularly used to characterize modern biological samples (D'Ambrosio, C.; Arena, S.; Salzano, A. M.; Renzone, G.; Ledda, L.; and Scaloni, A. Proteomics 2008 8, 3657-3666 (ref 5), their application in ancient materials is still at an early stage of progress, only few results being reported about ancient food samples (Yang, Y.; Shevchenko, A.; Knaust, A.; Abuduresule, I.; Li, W.; Hu, X.; Wang, C.; Shevchenko, A. J. Archaeol. Sci. 2014, 45, 178-186 (ref 6). In the absence of previous relevant evidence of cheese production and/or use, this study, undoubtedly has a clear added value in different fields of knowledge ranging from archaeometry, anthropology, archeology, medicine history to the forensic sciences.