Mohammadi Parisa, Maghboli-Balasjin Nasim
Faculty of Biological Sciences, Alzahra University, Vanak, Tehran, Iran.
Iran J Microbiol. 2014 Oct;6(5):361-70.
Biodeterioration is an irreversible damage that is caused by colonization of microorganisms on the surface of different materials. Among all microorganisms, fungi play an important role in deterioration of materials. Fungi can colonize on stone surfaces and by secreting different enzymes, organic and inorganic acids and pigments, can cause bio-weathering and changing not only the substrate materials but the color of stones. Furthermore, fungal mycelia can penetrate into the internal surfaces of stones and change the interior chemical contents of stones. Pasargadae including Cyrus the Great Tomb is entitled by UNESCO as one of the World Heritage Sites. This study was focused on the identification of fungi that were colonized on the tomb limestone monument.
Sampling of stone was carried out to identify inhabiting molds and yeasts. biochemical and microscopic methods were used for isolated strains. In addition, the Polymerase Chain Reaction (PCR) and sequencing of the PCR products were done. Finally, phylogenic tree was constructed basde on the sequences of ITs region.
The common inhabiting fungi which isolated from the tomb limestone belong to Caldosporium sp., Embellisia sp., Cryptococcus sp., Candida sp., Meyerozyma sp., Arthirinium sp., Ulocladium sp., Fusarium sp., Humicola sp. and Pseudozyma sp.. Stereomicroscopic and Scanning Electron Microscope images and XRD, were taken from pieces of stone samples and indicated the severe pattern damages such as pitting, biomineralization, etching and sugaring on the surfaces of stones.
生物劣化是由微生物在不同材料表面定殖所导致的不可逆损害。在所有微生物中,真菌在材料劣化过程中发挥着重要作用。真菌能够在石材表面定殖,并通过分泌不同的酶、有机和无机酸以及色素,引发生物风化,不仅改变基质材料,还会改变石材的颜色。此外,真菌菌丝体能够穿透石材的内表面,改变石材内部的化学成分。包括居鲁士大帝陵墓在内的波斯波利斯被联合国教科文组织列为世界遗产之一。本研究聚焦于对陵墓石灰石纪念碑上定殖的真菌进行鉴定。
对石材进行采样以鉴定栖息的霉菌和酵母菌。采用生化和显微镜方法对分离菌株进行研究。此外,进行了聚合酶链反应(PCR)及PCR产物测序。最后,基于ITS区域序列构建系统发育树。
从陵墓石灰石中分离出的常见栖息真菌属于弯孢霉属、饰孢霉属、隐球菌属、念珠菌属、梅耶酵母属、节菱孢属、格孢腔菌属、镰刀菌属、腐质霉属和假丝酵母属。对石材样品碎片进行了体视显微镜和扫描电子显微镜成像以及X射线衍射分析,结果表明石材表面存在严重的图案损伤,如麻点、生物矿化、蚀刻和糖化现象。