Comparative Analysis of the Structure of Buried and Surface Soils by Analysis of Microbial DNA

The microbiomes of the soils buried under earthwork structures of different age (burial mounds and defensive earth walls) and of surface soils were investigated. Microbial DNA was analyzed by quantitative PCR and sequencing of the 16S rRNA gene amplicons. Both microbial abundance and diversity in buried soils were found to be lower. The taxonomic structure of the buried soil microbiomes differed significantly from that of surface soils: the share of the bacterial phylum Verrucomicrobia was very low. The thickness of the earthwork structure should be sufficient to isolate soil from the effect of plant roots; otherwise, the microbiome may exhibit virtually no difference from that of surface soils. The degree of mineralization of stored organic matter (in the absence of inflow of fresh organic compounds) is probably the main factor affecting the structure of microbial communities in buried soils. The study did not reveal any properties of the microbiomes usable as markers of the type of buried soils.