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【目的】确定第98窟壁画表面白色污染物内微生物微观特征,分析其群落组成、结构特点及诱发壁画病害微生物产生的因素,为石窟寺保护和旅游管理提供建议。【方法】利用无菌手术刀收集壁画表面白色污染物样品;利用扫描电子显微镜(SEM)分析样品中微生物体微观形貌;通过提取样品总DNA、扩增细菌16S rDNA、构建克隆文库、测序和系统发生关系分析等技术研究壁画微生物群落组成与结构特点。【结果】壁画白色污染物中存在大量具有微生物特征的结构体,形态多呈短杆状和卵圆形,大小在(3.0 5.5)μm×(1.5 2.5)μm之间。共得到克隆文库序列111条,主要为变形菌门γ-变形菌亚门肠杆菌科(Enterobacteriaceae)与假单孢菌科(Pseudomonadaceae)成员。群落组成和结构分析表明所得序列主要隶属于肠杆菌属(Enterobacter)、埃希菌属(Escherichia)、固氮菌属(Azotobacter)、沙雷氏菌属(Serratia)和克雷伯菌属(Klebsiella);埃希菌属和肠杆菌属为优势属,分别占克隆文库中总序列的46.8%和35.1%,二者在自然界分布广泛,大多属于人类致病菌。【结论】莫高窟第98窟壁画表面白色污染物主要为病害细菌生长所形成的菌斑群落集成。变形菌门在壁画细菌克隆文库中占绝对优势,壁画病害微生物的出现和蔓延可能与该洞窟之前长期旅游开放存在一定关联。
【Objective】 The objective of this study was to determine the micro-characteristics of micro-organisms in the white fouling on the surface of the cave wall at Cave 98 and to analyze its community composition, structural characteristics and the factors that cause the frescos in the mural diseases, so as to provide suggestions for the conservation and tourism management of the cave temple. 【Method】 The white fouling samples on mural surface were collected by using sterile scalpel; the micro-morphology of micro-organisms in samples was analyzed by scanning electron microscope (SEM); 16S rDNA of bacteria was amplified by extraction of total DNA of samples; Phylogenetic relationships and other techniques to study the mural microbial community composition and structural characteristics. 【Result】 There were a large number of microbial structures in the white fouling of murals, mostly in the shape of short rod and oval with the size of (3.0 5.5) μm × (1.5 2.5) μm. A total of 111 cloned library sequences were obtained, mainly consisting of Enterobacteriaceae and Pseudomonadaceae members of the Proteobacteria. The composition of the community and the structure analysis indicated that the obtained sequences mainly belong to Enterobacter, Escherichia, Azotobacter, Serratia and Klebsiella. . The genus Escherichia and Enterobacter were the dominant genus, accounting for 46.8% and 35.1% of the total sequences in the cloning library, respectively. Both of them were widely distributed in nature and mostly belonged to human pathogenic bacteria. 【Conclusion】 The white fouling on the frescoes of Cave 98 in Mogao Grottoes is mainly due to the integration of plaque communities formed by the growth of disease bacteria. Proteobacteria accounted for the absolute advantage in the mural bacterial cloning library. The occurrence and spread of mural microbial pathogens may be related to the long-term tourism openness before the cave.