Bacterial DNA metabarcoding of lake sediment
Total DNA was purified from sediment and biofilm samples with the E.Z.N.A. Soil DNA Kit (Omega Bio-Tek), and the concentration in each extract was assessed using the Qubit High Sensitivity dsDNA Assay (Thermo Fisher Scientific). DNA metabarcoding library preparation and sequencing were carried out by Novogene Europe. The primers 341F (5-CCTAYGGGRBGCASCAG-3) (Herlemann et al., 2011) and 806R (5-GGACTACNNGGGTATCTAAT-3) (Apprill et al., 2015) were used to amplify the 16S V3-V4 rDNA region for bacteria.  The PCR products were purified using magnetic bead purification. Sequencing libraries were generated by attaching Illumina adapters. Obtained libraries were quantified, pooled in equimolar ratios, and sequenced on an Illumina platform 2x150 bp.