## 5 Conclusions  
Taken together, analyses of bacterial and fungal communities' biodiversity in bioenoses from historic sandstone Pergolas revealed that the observed changes were mostly associated with the biodeterioration patterns (BPs) (presence of mosses or lichen crusts). However, dominating microbial groups that correlate with seasonal changes were also identified. What is more, visible color changes in BPs may be caused by seasonal changes in the number of microorganisms capable of producing pigments. The above observation may be a starting point for the implementation of dedicated strategies for the protection of historical stone objects, taking into account the season of the year in which renovation works are carried out and depending on the type of BPs. The diversity of organisms in the biofilm ensures its stability throughout the year despite the differences recorded between winter and summer. Additionally, the maturity and stability of the biofilm present on stone surfaces of the Pergola may be the reason for the relatively low abundance of Cyanobacteria phylum representatives in the studied bioenoses because of the pioneer organisms (e.g., algae, autotrophic bacteria, etc.) have been replaced by successors. Moreover, a positive correlation between the presence of lichen crusts on the sandstone surface and the presence of lichenized fungi _Rhinocladiella_ and _Lecania_ as well as the presence of alkaliophilic bacterial genus _Truepera_ was found, whereas a negative correlation was observed for Acidobacteriaceae and Acetobacteraceae acidophilic bacterial families. Identified correlations give the evidence to the complex relationships between the organisms that build described biocenoses, but the functional analysis of the processes taking place on the surface of the historical sandstone in different seasons requires further research. In the next stage we would like to verify, which metabolic pathways dominate in a given season and which pathways are characteristic for a given BPs. Thus, metabarcoding analyses in combination with metabolic analyses will form the basis for the implementation of dedicated and more effective methods of removing biodeteriogens from the surfaces of historic buildings made of sandstone. This is an important issue in the context of the protection of sandstone objects in a moderate climate zone and taking into account the number of buildings made of sandstone or with elements made of this material. An additional conclusion is that metabarcoding researches seem to be an excellent and convenient method for analyzing the biodeterioration processes of stone monuments. It allows for quick and relatively accurate determination of the composition of biocenoses and, as a consequence, to predict its biodeteriorative potential. Metabarcoding provides a much larger amount of data in a short time compared to more conventional methods of identifying microorganisms. Metagenomic methods in combination with the metabolomics studies should allow conservators to determine the least destructive ways of cleaning historic buildings and ensuring optimal methods for their protection/preservation. **Supplementary Materials:** The following are available online at [[https://www.mdpi.com/2076-3](https://www.mdpi.com/2076-3)]([https://www.mdpi.com/2076-3](https://www.mdpi.com/2076-3)) 417/11/2/620/s1, Figure S1: Rarefaction curves for observed Amplicon Sequence Variants (ASVs) in each sample collected in winter (suffix W) and summer (suffix S) from the sandstone surfaces of the Northern Pergola at the Museum of King John III's Palace at Wilanow. Saturation curves are presented for bacterial (a) and fungal (b) ASVs, respectively; Figure S2. Identified bacteria (a) and fungi (b) at the class level in samples taken from the surface of the of the Northern Pergola at the Museum of King John III's Palace at Wilanow. One additional group was created to include the class with unspecified (i.e., '_p_ ) or uncertain (i.e., '_Unassigned_') taxonomic position assigned (_Unspecified_); Figure S3.