Beta-Diversity Enhancement by Archaeological Structures: Bacterial Communities of an Historical Tannery Area of the City of Jena (Germany) Reflect the Ancient Human Impact

Abstract

Soil samples taken during archaeological investigations of a historical tannery area in the eastern suburb of the medieval city of Jena have been investigated by 16S r-RNA gene profiling. The analyses supplied a large spectrum of interesting bacteria, among them Patescibacteria, Methylomirabilota, Asgardarchaeota, Zixibacteria, Sideroxydans and Sulfurifustis. Samples taken from soil inside the residues of large vats show large differences in comparison to the environmental soil. The PCAs for different abundance classes clearly reflect the higher similarity between the bacterial communities of the outside-vat soils in comparison with three of the inside-vat soil communities. Two of the in-side vat soils are distinguishable from the other samples by separate use of each abundance class, but classes of lower abundance are better applicable than the highly abundant bacteria for distinguishing the sampling sites by PCA, in general. This effect could be interpreted by the assumption that less abundant types in the 16S r-RNA data tend to be more related to an earlier state of soil development than the more abundant and might be, therefore, better suited for conclusions on the state of the soils in an earlier local situation. In addition, the analyses allowed identification of specific features of each single sampling site. In one site specifically, DNA hints of animal residue-related bacteria were found. Obviously, the special situation in the in-site vat soils contributes to the diversity of the place, and enhances its Beta-diversity. Very high abundancies of several ammonia-metabolizing and of sulphur compound-oxidizing genera in the metagenomics data can be interpreted as an echo of the former tannery activities using urine and processing keratin-rich animal materials. In summary, it can be concluded that the 16S r-RNA analysis of such archaeological places can supply a lot of data related to ancient human impacts, representing a kind of “ecological memory of soil”.

Low Abundant Bacteria Reflect Soil Specificity—Analysis of Bacterial Communities from Archaeological Investigation of Pre-Industrial Saline Ash Deposits of Bad Dürrenberg (Germany)

“…For the evaluation of the results, the data from the saline samples from Bad Dürrenberg were compared with the data of the soil samples from the ancient coal mine exploration shaft near Bennstedt [12] also by PCA. The results of earlier studies on soil samples from human impact areas suggested the high importance of lower abundance bacterial types for distinguishing the character of local soil bacterial communities [37]. Therefore, here, the data of the saline samples of Bad Dürrenberg were analyzed together here with the samples from Bennstedt by a PCA distinguishing the abundance classes of single OTUs.…”