麦积山石窟赋存环境中空气细菌的时空分布特征

【目的】空气微生物沉降及污染与文化遗产的微生物退化密切相关,本文对世界文化遗产地麦积山石窟赋存环境空气中细菌浓度和群落结构的季节性变化特征进行了系统研究,为石窟环境监测预警和文物预防性保护提供依据。【方法】利用生物气溶胶采样器,在2016年春、夏、秋和冬季分别采集空气样品;基于传统培养方法获得空气中细菌浓度及纯培养菌株;通过提取基因组DNA、扩增细菌16S rRNA、测序和系统发生树等分子技术研究细菌群落时空动态变化规律;结合环境监测数据,分析影响遗产地空气细菌变化的主要因素。【结果】监测期内,空气细菌浓度在(281.20–1409.20)CFU/m3之间,最高浓度出现在MJ4处的夏季,最低浓度出现在MJO处的春季;具有明显季节性变化特征,在空间层位分布上有所差异,但不显著(P0.05)。培养的细菌菌株经鉴定属于4个门11个属;芽孢杆菌属(Bacillus)、Paenarthrobacter、节杆菌属(Arthrobacter)、薄层菌属(Hymenobacter)和考克氏菌属(Kocuria)等为优势属。【结论】麦积山石窟空气细菌群落结构具有明显的季节性和空间分布动态变化特征;在石窟不同层位,空气中细菌群落分布与相对湿度、温度与降雨量相关;部分细菌种属如芽孢杆菌属、微球菌属(Micrococcus),为壁画及彩塑生物腐蚀的潜在病害菌;麦积山石窟及周边环境空气细菌的监测可为石窟保护和旅游开放管理提供重要参考。

Spatial and temporal distribution characteristics of the airborne bacteria in the Maijishan grottoes, China

Objective] The deposition of the airborne microorganisms and air pollution were closely related to the biodeterioration of the cultural heritage. In this study, a systematic survey of seasonal variation characteristics of bacterial concentration and community structure was carried out in the surrounding atmosphere of Maijishan Grottoes, a renowned cultural heritage site in China. The results will be helpful for the environmental monitoring and precaution of cave temples and preventive protection of cultural relics. Methods] The Bio-aerosol sampler was used for sampling in all seasons in 2016. Traditional culture-based method to acquire the airborne bacterial concentration information and purified strains; by the extraction of genomic DNA, amplification of bacteria 16S rRNA region, sequencing, and phylogenetic analysis, thereafter the bacteria community composition and distribution characteristics were clarified. Combined with environmental monitoring data, to find out the main factors which may responsible for the dynamic changes of the airborne bacteria. Results] The concentrations of culturable bacteria were in a range from 281.2 to 1409.2 CFU/m³, the highest and the lowest concentration appears at MJ4 in summer and at MJO in spring, which varied apparently with seasonal characteristics, but no significant difference among different sites. A total of 11 different bacterial genera that affiliated to four phyla were detected in this study, among which, Bacillus, Paenarthrobacter, Arthrobacter, Hymenobacter and Kocuria were dominant genera. Conclusion] The airborne bacterial community structures of the Maijishan grottoes show a dynamic characteristic of the seasonal variation and spatial distribution; RH, temperature and rainfall all have influenced on the airborne bacteria distribution in different layers of the Grottoes; some of the genus, such as Bacillus and Micrococcus, has potentials that could result in the biodeterioration of the ancient wall paintings and painted sculptures at this site; the monitoring of the airborne bacteria in its surrounding atmosphere of the Maijishan grottoes may contribute to the grottoes conservation and tourism management.