Investigation And Prevention Of Tue Typical Microbial Diseases On Feilaifeng Status In Hangzhou

Cultural relics are the precious wealth produced by our ancestors during the production and life in the past.They carry the splendid civilization of human and there are important historical,artistic and scientific values for us.However,cultural relics,especially for the outdoor immovable stoneworks,are subject to decay at the mercy of physical,chemical or biological weathering.Microorganisms including bacteria,fungi,algae and lichens are one of the major causes,which induce the damage of stone monuments and have received serious attention from conservators and conservation scientists.Feilaifeng coantains the biggest group of statues in Zhejiang Province,which has a very important religious and artistic value.It is not only an important nation-level preservation unit of cultural relics,but also a main part of the World Heritage,West Lake Cultural Landscape of Hangzhou.However,it is currently suffering from the degterioration by microbes,and the value of cultural relics has been damaged.In the present study,taking Feilaifeng site as the example,we aimed to identified the typical strains of the microbial communities on stone relics,and assess their role in the deterioration of the stone relics.With DNA sequencing technique,the green moss was identified as Frullaniaceae and Taxiphyllum,and the alga with orange was identified as Trentepohlia.Patinas,which may be caused by microorganisms,have widely covered the surface of the limestone in the site and have severely diminished the esthetic value of the statues.Using the analysis of characterization techniques,such as Optical Microscope,Scanning Electron Microscope and Energy Dispersive Spectroscopy,and X-ray Diffraction,we found that patina was consisting of CaCO₃.Five bacterial and ten fungal genera were isolated and identified from the sample of patina,and some of the microbles related to the formation of patina,which suggested that both aesthetic and deteriorated damage could be induced by patina.Colletotrichum was first found to relate to the precipitation of calcium carbonate.Colletotrichum could use organic acids as their carbon source during the proliferation,and the consumption of the acids promotes the increase of pH,which will promote to the formation of CaCO₃.In order to prevent the deterioration of stone relics induced by microorganisms,we assessed the effectiveness of three inorganic and six organic biocides in inhibiting microbial colonization.After the determination of minimal inhibit concentration of the biocides to microorganisms and comparing their antimicrobial efficacy using the inhibition zone method,we suggested that AW-600,which the active ingredients is octhilinone,was the most effective biocide,and 0.5%was the optimal applied concentration.The biocide was then tested in situ.Although no colonies were identified on the surface after the application of the biocide,recolonization of microorganisms was observed within a short-time period after the treatment.The ability of the biocide to inhibit microbial growth decreased with the decrease in its concentration,and AW-600 could be easily leached out of the limestone by frequent rainfall,which could be the reason of the recolonization for a short time.However,this would be modified when AW-600 was mixed with pure acrylic emulsion,which suggested a feasible strategy to treat the damage induced by microbes on Feilaifeng limestone.In conclusion,the study identified the microbial communities on stone relics,investigated the process and mechanisms of the biodeterioration of stoneworks induced by these microorganisms and assessed the effectiveness of different biocides to inhibit the proliferation of bacteria and fungi.It provides some insights for the conservators on the knowledge about the process of the occurrence and development of microbial diseases and how to protect Feilaifeng limestone from the degradation of microorganisms.And the comprehensive and systemic methods in this study could be helpful to establish a canonical protocol for the microbial control of immovable stone relics.