Biodeterioration of binding media in tempera paintings by Streptomyces isolated from some ancient Egyptian paintings

Abstract

Eight out of 46 Streptomyces isolates representing highest deterioration symptoms of disfiguration and scaling were isolated from mural paintings within tombs at Tell Basta and Tanis, Lower Egypt. These isolates were identified using traditional and 16S rDNA sequencing methods as Streptomyces albidofuscus, Streptomyces ambofaciens,Streptomyces canarius, Streptomyces chibaensis, Streptomyces coelicolor,Streptomyces corchorusii, Streptomyces nigrifaciens and Streptomyces parvullus. These identified Streptomyces isolates decomposed animal glue into amino acids with a high percentage of L-glutamic acid and ammonia as end product, depolymerized arabic gum into free mono-sugars, decomposed egg yolk into amino acids with low percentage of L-glutamic acid and ammonia and decomposed bees wax enzymatically into short chains of stearic acid. Finally, these isolates caused flaking of paintings layers due to penetration of filamentous mycelium within painting layers with the assistance of enzymatic hydrolysis. Key words: Animal glue, arabic gum, bees wax, biodeterioration, egg yolk,Streptomyces, Tell Basta, Tanis, Egyptian tombs.