The Local Ecological Memory of Soil: Majority and Minority Components of Bacterial Communities in Prehistorical Urns from Schöps (Germany)

Soil samples from five iron-age urns and five outside reference samples are investigated by 16S RNA sequencing (ngs) to evaluate the effect of the urns on the soil bacterial diversity. The urns are approximately 2000 years old and had been found during an archaeological excavation of the wet subground of an agricultural used area. All ten samples show similar distribution of phyla. Some major components show differences between the inside-urn and the outside-urn samples. Thus, the interior of urns is marked by a slightly enhanced percentage of Actinobacteria in comparison with the reference samples, whereas no difference between inside-urn samples and reference samples were found in the Chloroflexi content. Between the minor components, some operational taxonomic units (OTUs) could be proved which were found in several urns, but in no reference samples, among them the group TSCOR001-H18 (bacilli), Fodinicola and Angustibacter, NS11-12 marine group and the group S15-21. In addition, several OTUs were detected in single urns, which had been not provable in all other samples. The comparison between the individual urns and between urns and reference samples suggest that the minor components can be regarded as reflecting a signature-like sample-specific soil bacterial DNA pattern, which might become interesting in future investigations on the comparison of archaeological excavation sites and for the registration of bacterial diversity and gene resources at these places.