# Biological Risk for Hypogea: Shared Data from
## 3 Results
### The Ancient Tombs of the Baekje Dynasty  
#### 3.2.1 Recurrent Biodeterioration Phenomena  
Considerable biodeterioration phenomena took place in both of the analysed tombs with changes occurring after the opening and with further intervention procedures. In the conservation history of Tomb No. 6, heavy rainfall in Gongju in 1995 led to leakage, which caused blue-green algae, such as _Lynghya_ spp. and _Gloecapsa_ spp. which spread throughout the tomb [83; 84]. Since blue-green algae causes colouration and erosion of the structure, they were removed and subsequently no secondary damage caused by the algae was confirmed by a detailed ecosystem study after its removal [90]. In 1997, the Ancient Tombs in Songsan-ri, Gongju were permanently closed to preserve the original state of the mural paintings. Research on microbial distribution of Tomb No. 6 was first conducted in 2010 and twelve species of fungi were identified (e.g., _Acremonium_ spp., _Aspergillus_ spp., _Epicoccum_ spp., _Cladosporium_ spp., _Penicillium_ spp., _Fusarium_ spp., were found in the main chamber [55]. Bacteria belonged to Actinobacteria (three strains), Firmicutes (seven strains) and Proteobacteria (two strains). _Bacillus_ sp. resulted as the dominant strain and _B. simplex_ was also discovered on the wall surface. After some negative results were produced with microclimatic conditioning, studies were conducted to monitor the microbial distribution of the ancient tombs. Before entering the main chamber of Tomb No. 6, where the wall paintings are present, a person (i.e., visitor, operator) must pass through three buffer zones. The microorganism distribution tendedto decrease upon entering the main chamber, due to the buffer activity of such areas caused by the inflow of outdoor air. _Aspergillus_, _Cladosporium_, _Penicillium_, _Bacillus_, and _Pseudomonas_ genera were isolated in the air and _Aspergillus_ was also identified on the bricks and walls. Soil microorganisms of the genus _Bacillus_, which seem to have flowed inside the tomb from the soil environment, were the dominant bacteria [56]. In a further study, strains collected in the air (_Doratomyces_, _Engyodontium_, _Fusarium_, _Aspergillus_ genera) were identified in all four cardinal points of the walls [85]. Since 2008, numerous in-depth studies have been conducted on Tomb No. 1 which was closed in 1971 to preserve the wall paintings, along with an analysis of the biological distribution focusing on discoloured areas on the walls of the main chamber as well as the soil. As a result, 16 bacteria species were identified, including _Actinomycetes_ and a total of 15 fungal species (four species of _Penicillium_, three species of _Aspergillus_, one species of _Fusarium_, one species of _Trichoderma_, and six unidentified species) were found. The green specimens collected at the entrance of Tomb No. 1 were microalgae (_Apatococcus_, _Chlorella_, _Trebouxia_, and _Stichococcus_), and cyanobacteria (_Chroococcus_) [86]. Results of microbial distribution monitoring performed from 2016 to 2018 highlighted a decrease in microbial numbers upon entering the ancient tomb (entrance \(>\) outside \(>\) antechamber \(>\) corridor \(>\) main chamber). The highest airborne microbial distribution was found to be at the entrance as insects inhabiting the space and the air inflow while entering the tomb stationed there for a long time. _Cladosporium_, _Penicillium_, and _Bacillus_ were dominant airborne microorganisms and _Bacillus_, _Cupriavidus_, and _Streptomyces_ were identified on all the walls of the main chamber. _B. cereus_, _B. megaterium_, _Dermococcus nishinomiyaensis_, _Mucor_ sp., _Rhizomucor_ sp., and _Penicillium_ sp., identified on the walls were equally represented in the air. Accordingly, it was concluded that microorganisms in the air can harm the wall paintings when they settle and grow on the walls [59; 60]. Patinas presumed to be microorganisms were observed on the walls of the main chamber in Tomb No. 1 (Figure 4).