Fig. 1

Schematic representation of the experimental design. Blue colour corresponds to the comparison of the commercial kits. PL—PureLink™ Microbiome DNA Purification kit, ZR—ZymoBIOMICS™ DNA Miniprep kit; M—suspension mixture, P—pellet, S—supernatant. Purple colour corresponds to the storage conditions experiment. Marked with the red arrow C—control zero-point sample, analysed within two hours after sample collection. Samples marked with purple arrows were stored at different temperature conditions: RT at room temperature, 4 C at + 4 °C, -20 C at -20 °C (these samples were taken from the same tubes stored at corresponding temperature), -20 C new—two independent aliquots stored at -20 °C and excluded from the freezing-thawing cycle. Samples stored at different temperature conditions were analysed weekly during the three weeks period (1, 2, 3); 200 µl sample aliquots were subjected to the DNA extraction