The identification of wool by the number of keratinolytic microorganisms in the ground of ancient and medieval burials

The paper describes the method for determining the initial presence of wool products in the burial rite of several cultures of the Bronze Age and the Middle Ages. The method is based on the analysis of the number of keratinolytic fungi in soils. Keratin is a proteinaceous biopolymer, which is a part of wool, leather, feather, and other materials. Its decomposition in soil occurs with the participation of a small group of soil fungi with keratinolytic activity. The ingress of wool and other keratin-containing substrates in the soil of archaeological monuments in antiquity provoked the sharp increase in the number of keratinolytic fungi. After the entire keratin-containing substrate was utilized, these fungi became dormant forms (cysts and spores), and in this state they could persist up to nowadays. The presence of keratinolytic microorganisms has been determined using the plate method - by direct counting of colony-forming units in media with wool brought into the substrate as the sole source of nutrients for soil microorganisms...