Bacterial and Fungal Diversity Inside the Medieval Building Constructed with Sandstone Plates and Lime Mortar as an Example of the Microbial Colonization of a Nutrient-Limited Extreme Environment (Wawel Royal Castle, Krakow, Poland).

Dyda Dyda,Kwiatkowska-Kopka Kwiatkowska-Kopka,Sklodowska Sklodowska,Pyzik Pyzik,Wilkojc Wilkojc

doi:10.3390/microorganisms7100416

Dyda Dyda, Kwiatkowska-Kopka Kwiatkowska-Kopka + Show 3 more

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https://doi.org/10.3390/microorganisms7100416

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Journal: Microorganisms	Publication Date: Oct 3, 2019
Citations: 16	License type: CC BY 4.0

Affiliation: University of Warsaw

Abstract

Biodeterioration is a serious threat to cultural heritage objects and buildings. The deterioration of a given material often incurs irreparable losses in terms of uniqueness and historical value. Hence preventive actions should be taken. One important challenge is to identify microbes involved in the biodeterioration process. In this study, we analyzed the microbial diversity of an ancient architectonical structure of the Rotunda of Sts. Felix and Adauctus, which is a part of the Wawel Royal Castle located in Krakow, Poland. The Rotunda is unavailable to tourists and could be treated as an extreme habitat due to the low content of nutrients coming either from sandstone plates bound with lime mortar or air movement. Microbial diversity was analyzed with the use of the high-throughput sequencing of marker genes corresponding to fragments of 16S rDNA (for Bacteria) and ITS2 (internal transcribed spacer 2) (for Fungi). The results showed that the microbial community adhered to wall surfaces is, to a large extent, endemic. Furthermore, alongside many microorganisms that could be destructive to masonry and mortar (e.g., Pseudomonas, Aspergillus), there were also bacteria, such as species of genera Bacillus, Paenisporosarcina, and Amycolatopsis, that can positively affect wall surface properties by reducing the damage caused by the presence of other microorganisms. We also showed that airborne microorganisms probably have little impact on the biodeterioration process as their abundance in the microbial community adhered to the ancient walls was very low.

Highlights

Cultural heritage buildings and objects are heterogeneous habitats, that can be colonized by various microorganisms
We sought to characterize the microbiome associated with the remains of an excavated ancient structure built in the 10th/11th century
Its interior exhibits the characteristics of an extreme environment, primarily because of nutrient limitation, poor air exchange, unstable humidity and high salinity reflected by the presence of efflorescence on internal walls (Figures 1b and 3b)

Summary

Introduction

Cultural heritage buildings and objects are heterogeneous habitats, that can be colonized by various microorganisms. The following three main types of biodeterioration processes are known: (1) chemical, caused by organic and inorganic acids and chelating compounds; (2) mechanical, caused by the growth of microorganisms; (3) fouling or soiling as the result of biofilm formation [2,3]. Taxonomic groups shown to be involved in the biodeterioration process include Bacteria, Archaea, Cyanobacteria, Fungi, and Lichens [2,3]. It seems that bacteria and fungi contribute the most to the destruction of valuable historical objects. Bacteria and fungi usually have high growth rates and may tolerate extreme environmental conditions, such as low nutrient concentrations, wide ranges of pH and temperature as well elevated concentrations of compounds that are toxic to other organisms. It is assumed that natural stone surfaces are first colonized by chemoorganotrophic or heterotrophic bacteria, which produce organic matter, followed by fungi [4]

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