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Wooden shipwrecks are a significant part of the underwater cultural heritage. In 2007, the Nanhai No. 1 shipwreck was salvaged from the seabed and moved into the Marine Silk Road Museum, where it is still stored in a water tank. We analysed the microbial communities colonizing the hull surface of the Nanhai No. 1 shipwreck during storage. Six samples exposed to air were collected from different spots of the ship that exhibited obvious microbial plaques. High-throughput sequencing revealed the bacterial community includes both aquatic and terrestrial species, while in the fungal community, Fusarium was the most abundant genus across all samples and accounted for 84.91% to 98.40% of the total community composition. Two Fusarium species were isolated from the samples and were identified as F. solani and F. oxysporum. Both of the isolates were able to degrade cellulose, but only F. solani had the ability to degrade lignin. Antimicrobial efficacy in inhibiting the growth of Fusarium was assessed with five kinds of biocides, and isothiazolinones exhibited specific inhibition of Fusarium growth. These results provide critical background information to protect and reduce the biodegradation and destruction of this important historical shipwreck, and inform efforts to protect other similar artifacts.

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Research on the microbial communities that colonize stone monuments may provide a new understanding of stone biodeterioration and microbe-induced carbonate precipitation. This work investigated the seasonal variation of microbial communities in 2016 and 2017, as well as its effects on stone monuments. We determined the bacterial and fungal compositions of 12 samples from four well-separated geographic locations by using 16S rRNA and internal transcribed spacer gene amplicon sequencing. Cyanobacteria and Ascomycota were the predominant bacterial and fungal phyla, respectively, and differences in species abundance among our 12 samples and 2 years showed no consistent temporal or spatial trends. Alpha diversity, estimated by Shannon and Simpson indices, revealed that an increase or decrease in bacterial diversity corresponded to a decrease or increase in the fungal community from 2016 to 2017. Large-scale association analysis identified potential bacteria and fungi correlated with stone deterioration. Functional prediction revealed specific pathways and microbiota associated with stone deterioration. Moreover, a culture-dependent technique was used to identify microbial isolates involved in biodeterioration and carbonatogenesis; 64% of 85 bacterial isolates caused precipitation of carbonates in biomineralization assays. Imaging techniques including scanning electron microscopy with energy-dispersive spectroscopy, X-ray diffraction, and fluorescence imaging identified CaCO3 crystals as calcite and vaterite. Although CaCO3 precipitation induced by bacteria often has esthetically deleterious impacts on stone monuments, this process may potentially serve as a novel, environmentally friendly bacterial self-inoculation approach to the conservation of stone.IMPORTANCE Comprehensive analyses of the microbiomes associated with the deterioration of stone monuments may contribute to the understanding of mechanisms of deterioration, as well as to the identification of potentially beneficial or undesirable microbial communities and their genomic pathways. In our study, we demonstrated that Cyanobacteria was the predominant bacterial phylum and exhibited an increase from 2016 to 2017, while Proteobacteria showed a decreasing trend. Apart from esthetic deterioration caused by cyanobacteria and fungi, white plaque, which is composed mainly of CaCO3 and is probably induced by Crossiella and Cyanobacteria, was also considered to be another threat to stone monuments. We showed that there was no significant correlation between microbial population variation and geographic location. Specific functional genes and pathways were also enriched in particular bacterial species. The CaCO3 precipitation induced by an indigenous community of carbonatogenic bacteria also provides a self-inoculation approach for the conservation of stone.

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The Mausoleum of the Dingtao King (termed 'M2') is a large-scale huangchang ticou tomb that dates to the Western Han Dynasty (206 B.C.-25 A.D.). It is the highest-ranking Han Dynasty tomb discovered to date. However, biodeterioration on the surface of the tomb M2 is causing severe damage to its wooden materials. The aim of the present study was to give insight into the fungal communities colonized the wooden tomb. For this purpose, seven samples were collected from different sections of the tomb M2 which exhibited obvious biodeterioration in the form of white spots. Microbial structures associated with the white spots were observed with scanning electron microscopy. Fungal community structures were assessed for seven samples via a combination of high-throughput sequencing and culture-dependent techniques. Sequencing analyses identified 114 total genera that belonged to five fungal phyla. Hypochnicium was the most abundant genus across all samples and accounted for 98.61-99.45% of the total community composition. Further, Hypochnicium sp. and Mortierella sp. cultures were successfully isolated from the tomb samples, and were distinguished as Hypochnicium sp. WY-DT1 and Mortierella sp. NK-DT1, respectively. Cultivation-dependent experiments indicated that the dominant member, Hypochnicium sp. WY- DT1, could grow at low temperatures and significantly degraded cellulose and lignin. Thus, our results taken together suggest that this fungal strain must be regarded as a serious threat to the preservation of the wooden tomb M2. The results reported here are useful for informing future contamination mitigation efforts for the tomb M2 as well as other similar cultural artifacts.

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The historical relics exposed to the natural environment during the long-term were vulnerable to microbial invasion. According to some new studies, microorganism of Pseudonocardia may is one of the main groups on the surface of mural paintings and petroglyphs, causing damage to the paints. Based on recent research progress, we reviewed the phenomenon according to the relationship between the ancient paintings and the growth conditions of Pseudonocardia, which could provide a new theory basis for the protection of cultural relics especially mural paintings and petroglyphs.

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OBJECTIVE: In order to study the microorganisms on the surface of the ancient stones in Yungang Grottoes and nearby rock samples, a rapid microbial detection assay was designed. METHODS: The microbial community composition from the rock samples of the Yungang Grottoes and nearby was analyzed by PCR-DGGE. RESULTS: According to the phylogenetic analysis, the microbes from the rock samples of Yungang Grottoes were divided into four groups: Gamma-proteobacteria, Sphingobacteria, Alpha-proteobacter and Actinobacteria. By aligning the sequencing results in GenBank, Gamma-proteobacteria, Firmicutes and Alpha-proteobacter were found in the rock samples near Yungang Grottoes. CONCLUSION: Our research successfully detected the microbial community composition on the surface of the rock samples in and near the Yungang Grottoes, which brought us significant theoretical basis for the future protection of the Yungang Grottoes. We also proved that the combination of DGGE and molecular cloning was a useful, rapid and accurate method for detecting the microbial community composition on stone relics.

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