ACTINOBACTERIA AS A COMPONENT OF MICROBIAL COMMUNITY FORMED ON ROCK PAINTINGS OF MAGURA CAVE, BULGARIA
MILENA MITOVA*, MARIA IVANOVA, MICHAIL ILIEV
Department of General and Industrial Microbiology, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
*Corresponding author: mmitowa@abv.bg
Keywords: Biodeterioration, conservation, bat guano, Actinobacteria, Magura cave, rock paintings
Abstract: The Magura Cave is located in Northwestern Bulgaria. The cave contains an impressive display of prehistoric paintings made of guano feces of cave-dwelling bats. Many different types of microorganisms may grow on such substrate under favorable environmental conditions and have a biodeterioration effect on the paintings. Among numerous biological agents, Actinobacteria play a critically important role in stone deterioration. They cause various types of damage to stone as a result of biofilm formation, physical penetration into the substrate and chemical reaction with the substrate by pigments.
The aim of the present study was to investigate the Actinobacteria diversity from samples derived from Gallery with paintings, Magura cave. For this purpose the isolates obtained were identified on the basis of morphological, physiological and biochemical characteristics. The molecular approach, including the amplification of 16S rDNA was also used. The antagonistic effect of the isolates as well as their sensitivity to different biocides was tested too.
The results showed that the isolates are closed to the genus Streptomyces. The isolates have relatively strong antagonistic effect against Bacillus, Sphingobacterium, Sarcina and Pseudomonas, which were used as test microorganisms. The biocides tested inhibited the isolates at concentration 1% and the most active biocide against these isolates is Cu2+.
The results obtained are important for the development of correct conservation and restoration strategies of the unique rock paintings.