Identification of microorganisms harmful to human health inhabiting historical surfaces using MALDI TOF mass spectrometry and DNA sequencing and their elimination using ethanol in the mist form

Abstract

The aim of this study was to test the biocidal effectiveness of the disinfection technique using 90 % ethanol in the form of mist on wall painting layers in the block with inventory number A-28 located in the A-BSM.

Using the DNA sequencing and MALDI TOF methods, species of bacteria and fungi inhabiting the wall surfaces were identified. Then, 90 % ethanol in the form of mist was applied to the surfaces. The number and species composition of bacteria and fungi as well as the colour of the painting layers were determined before and after disinfection.

On the surface of the 10 examined areas, 10 species of bacteria, 3 species of yeast and 7 species of mould were identified, some of which are opportunistic pathogens. After the use of ethanol in the form of a mist, the reduction in the number of bacteria was 70.4 % to > 99 %, and of fungi was in the range of 78.2 % - > 99 %. It was also shown that disinfection with ethanol in the form of a mist did not affect the colour components of the painting layers.

To sum up, disinfection of painting layers using 90 % ethanol in the form of mist has a high biocidal effectiveness and does not cause a change in the colour of the painting layers, so it can be used for decontamination on the interior walls of historic buildings in A-BSM.