Various bacteria, streptomycetes and fungi were isolated from the damaged frescoes and building materials in the Cathedral of the Nativity of the Virgin at the Pafnutii-Borovskii Monastery. Growth of micro-organisms was associated with the formation of a compact yellowish-white coating on the cleared and restored frescoes, plaster and brick, and with the powdery destruction of building stone and brickwork at the lower parts of the walls. Evidence was given to support the hypothesis that, although heterotrophic micro-organisms could use organic substances of dust, admixtures in plaster, binding medium of paints and restoration material as nutrient sources for growth on inorganic building materials and frescoes, it is in fact the trophic interrelationships which play the main role within microbial communities of this type. It was demonstrated that fungi and streptomycetes could produce enzymes hydrolysing bacterial and fungal cell walls as well as bacterial extracellular polysaccharides.