Table_1_Exploring the key deteriorative microorganisms on ancient ivories unearthed from the Sanxingdui Ruins site during temporary cold storage.DOCX

IntroductionThe ancient ivories unearthed from the Sanxingdui Ruins site are valuable cultural relics, however, the microbial biodeterioration on ivories during temporary cold storage poses a great threat to their later long-term preservation.MethodsHere, the combination of high-throughput sequencing and biochemical assays was applied for the in-depth investigation of the key deteriorative microorganisms colonizing on the ivories and the tracing of their origin, as well as the assessment of the ethanol disinfection impact on the microbial communities on ivories.ResultsIt was observed that the surfaces of ivories were scattered by the fungal patches of white, dark grey, and hedge green colors during cold storage. The high-throughput sequencing results showed that the genera Mortierella (38.51%), Ilyonectria (14.43%), Penicillium (1.15%), and Aspergillus (1.09%) were the dominant fungi, while Pseudomonas (22.63%), Sphingopyxis (3.06%), and Perlucidibaca (2.92%) were the dominant bacteria on ivories. The isolated Aspergillus A-2 resulted in the highest amount of calcium releasing from the degradation of hydroxyapatite (HAP), the main component of ivory, by the organic acids produced, including oxalic acid and citric acid. The fast expectation-maximization for microbial source tracking (FEAST) analysis revealed that the majority of the fungi (57.45%) and bacteria (71.84%) colonizing on the ivories were derived from the soils surrounding ivories in the sacrifice pits, indicating soils as the primary source for the spoilage microbes growing on ivories. The dominant strains could degrade cellulose, the key components of wet cotton towels commonly applied on ivories for moisture maintenance, aiding the spoilage microbes colonizing on ivories. Notably, the ivory disinfection with 75% ethanol during the cleansing significantly decreased the relative abundance of the dominant genera of Ilyonectria, Aspergillus, and Pseudomonas, with Mortierella becoming the dominant one on ivories.DiscussionTogether, the fungi, particularly Aspergillus and Penicillium, played a significant role in the microbial biodeterioration of unearthed ancient ivories by producing the organic acids. These results may improve the control of the microbial biodeterioration and develop more efficient strategies for the long-time conservation of unearthed ancient ivories and other cultural relics.

引言：自三星堆遗址出土的古代象牙是珍贵的文化遗产，然而，在临时冷藏过程中，象牙上的微生物生物降解对其长期保存构成了严重威胁。方法：在本研究中，通过结合高通量测序和生化检测，对栖息在象牙上的关键降解微生物进行了深入研究，追溯了其来源，并对乙醇消毒对象牙上微生物群落的影响进行了评估。结果：观察到在冷藏过程中，象牙表面散布着白色、深灰色和常春藤绿色的真菌斑点。高通量测序结果显示，Mortierella (38.51%)、Ilyonectria (14.43%)、Penicillium (1.15%) 和 Aspergillus (1.09%) 是主要的真菌，而 Pseudomonas (22.63%)、Sphingopyxis (3.06%) 和 Perlucidibaca (2.92%) 是主要的细菌。分离得到的 Aspergillus A-2 通过产生的有机酸，包括草酸和柠檬酸，导致羟基磷灰石（HAP）——象牙主要成分的降解，释放出最高的钙量。快速期望最大化微生物来源追踪分析（FEAST）显示，栖息在象牙上的大多数真菌（57.45%）和细菌（71.84%）源自牺牲坑中象牙周围的土壤，表明土壤是导致象牙上微生物腐败生长的主要来源。优势菌株能够降解纤维素，这是湿棉毛巾的关键成分，常用于象牙的保湿，有助于栖息在象牙上的腐败微生物的生长。值得注意的是，在清洁过程中使用75%的乙醇对象牙进行消毒，显著降低了Ilyonectria、Aspergillus 和 Pseudomonas 主导菌属的相对丰度，使 Mortierella 成为象牙上的主导菌属。讨论：综合来看，真菌，尤其是 Aspergillus 和 Penicillium，通过产生有机酸，在出土古代象牙的微生物生物降解中发挥了重要作用。这些结果可能有助于控制微生物的生物降解，并开发出更有效的策略，以实现出土古代象牙及其他文化遗产的长期保存。