燎祭对三星堆古象牙周际土壤微生物群落的影响

The influence of Liao Festival on the microbial community of the surrounding soil of ancient ivory in Sanxingdui

三星堆遗址四号祭祀坑象牙表面留有灼烧痕迹,其上附着黑色灰烬.为了解黑色灰烬土对古象牙保存的影响,本研究比较了灰烬土和对照黄土的理化性质,并对其中微生物进行了高通量测序和多组学分析.结果发现,灰烬土中水分和有机碳含量显著高于未灼烧黄土(P<0.05).高通量测序显示,灰烬土和黄土中均以变形菌门(Proteobacteria)和担子菌门(Basidiomycota)占优势,灰烬土中含有更高丰度的细菌属Methylotenera、Flavobacterium和Ac⁃idovorax,以及真菌属Mortierella、Penicillium和Aspergillus.代谢组显示,灰烬土中L-苹果酸、泛酸等有机酸显著低于黄土,而对古象牙腐蚀性更强的草酸则显著高于黄土(P<0.05).因此,烧灼引起土壤理化性质的显著变化,使灰烬土中含有更高水分和有机碳,以及更低pH值,其微生物群落结构和组成改变导致草酸增高,增加了出土古象牙的腐蚀风险.

The burning marks from Liao Festival with the black ash on the surface of the ancient ivory unearthed from the sacrificial Pit 4 are conspicuous.To understand the impact of black andisols on the preservation of ancient ivory,this study compared the physicochemical properties of the black andisols with the control of unburned loess and conducted the high-throughput sequencing and multi-omics analysis on their microbial community.The results showed that the moisture and organic carbon content in the andisols were significantly higher than those in the loess(P<0.05).High throughput sequencing showed that Proteobacteria and Basidiomycota were dominant in both andisols and loess,while the former contained the higher abundance of bacterial genera Methylotenera,Flavobacterium,and Acidovoorax,as well as fungal genera Mortierella,Penicil⁃lium,and Aspergillus.Metabolomics analysis showed that the organic acids,including L-malic acid and pan‐tothenic acid,in andisols were significantly lower than those in loess,while oxalic acid,the more corrosive acid to ancient ivory,was significantly higher than that in loess(P<0.05).Accordingly,burning in the sacrificial pits caused the significant changes in soil physical and chemical properties,resulting in higher moisture and organic carbon content in andisols,as well as lower pH,which might bring about the change of the structure and composition of the microbial community and the increase of oxalic acid produced,eventually raising the risk of ancient ivory corrosion.