Five commercially available DNA isolation kits were compared: DNeasy Blood & Tissue Kit (Qiagen; DNE(Q)), GeneMATRIX Environmental DNA & RNA Purification Kit (Eurx; ENV(E)), GeneMATRIX Soil DNA Purification Kit (Eurx; SOI(E)), E.Z.N.A. Soil DNA Kit (Omega Bio‐tek; SOI(O)) and E.Z.N.A. Water DNA Kit (Omega Bio‐tek; WAT(O)). The selected methods are commonly used in metabarcoding surveys (Kaden and Krolla‐Sidenstein, 2015 (link); Braun and Szewzyk, 2016 (link); Wang et al., 2018 (link); Gołębiewski and Tretyn, 2019 (link); Jeunen et al., 2019 (link)). All isolation steps were performed according to the manufacturer's instructions. Finally, the DNA was eluted or suspended in 100 μl of nuclease‐free water (GE Healthcare).