墓室酥碱砖壁画及其环境的真菌多样性分析

【背景】酥碱是威胁古代墓室砖壁画保存的主要病害之一,水分和盐分共同作用下壁画产生酥碱病害,而其中真菌类群、来源及耐盐性鲜有报道。【目的】比较敦煌汉墓、晋墓和嘉峪关五号墓内砖壁画酥碱样品及其赋存环境空气中可培养真菌的群落组成、多样性及耐盐性,为砖壁画的防护提供理论依据。【方法】运用扫描电镜观察酥碱样品微观形貌,并结合能谱、X射线衍射进行成分分析;对样品培养、分离、纯化获得真菌纯菌株,运用形态和分子生物学技术鉴定种属;利用梯度含盐培养基研究菌株的耐盐性。【结果】墓室酥碱样品及环境空气中青霉属(Pencillium)、曲霉属(Aspergillus)和枝孢属(Cladosporium)丰度较高,为优势属;其他菌属包括镰孢菌属(Fusarium)和毛壳菌属(Chaetomium)为稀有属。三座墓室砖壁画酥碱中均存在烟曲霉(A.fumigatus)、花斑曲霉(A.versicolor)以及黄灰青霉(P.aurantiogriseum);酥碱样品与墓室内外空气中分离获得的真菌类群间有一定相似性。多数菌株可在含15%NaCl的培养基上生长,一株产黄青霉(P. chrysogenum)甚至可在30%盐浓度条件下生长。【结论】青霉属和曲霉属为墓室共有优势菌,多数菌株有较强的耐盐性。

Fungal diversity of brick murals with salt efflorescence and their surroundings in different ancient tombs

Background] Salt Efflorescence is one of the major diseases caused by combined action of humidity and salt which threated the preservation of ancient wall paintings, but the fields like composition of fungi, its origin and salt tolerance have seldom been reported. Objective] This study aimed at exploring the community difference of culturable fungi that isolated from brick murals with salt efflorescence disease and their surroundings in tombs, including Dunhuang Han dynasty tomb, Dunhuang Jin dynasty tomb, and Jiayuguan No. 5 tomb, meanwhile, it has purpose to explore the halotolerant ability of the isolated fungal strains in order to provide theoretical basis for better conservation of the brick-tomb wall paintings. Methods] The surface morphology and crystal phase of samples were analyzed by scanning electron microscope combined with energy dispersive spectrometer (SEM-EDS) and X-ray diffraction (XRD). The culture-dependent method was employed to isolate fungal strains, and to combine with molecular techniques for identification, the community composition and structure characteristics of fungi were identified thereafter. Halotolerancy of all the isolated strains were determined by salt-gradient culture medium method. Results] The dominant genera of the cultivated fungal genus were Penicillium, Aspergillus, Cladosporium, and the other groups including Fusarium and Chaetomium were rarely isolated. All of the salt efflorescence samples have some common species, such as A. versicolor, P. Aurantiogriseum and A. fumigatus. The community compositions of fungi isolated from the efflorescence samples were similar with their surrounding airborne samples. Most of the isolated strains could grow on culture medium containing 15% sodium chloride, a strain of P. chrysogenum do have their growth even in the 30% salt concentration. Conclusion] Pencillium and Aspergillus were dominated in different ancient tombs, most of the fungal strains most of the strains have relatively strong capacity of salt tolerance.