title: Metagenome of soil Mg_141
design: Metagenomic libraries were prepared using the NEBNext Ultra II DNA Library Prep Kit from NEB with some modifications to the manufacturer's protocol. Fifteen nanograms of metagenomic DNA were fragmented to 400-500 base pairs on a Covaris S220 instrument using microTUBE-50 AFA fiber screw-cap tubes in 50 or 100 microliters of sterile water. The fragmented DNA was purified and concentrated using AMPURE XP magnetic particles from Beckman Coulter, the particles being mixed with DNA at a ratio of 1:1.6, respectively. Purified and fragmented DNA were used in reactions for end completion, adenylation of 3'-ends, and ligation of NEBNEXT Adapter for Illumina adapters. DNA with attached adapters was treated with USER enzyme from NEB to remove uracil from adapters and "open" their hairpin structures, then purified using AMPUR XP magnetic particles mixed with DNA again at a ratio 0:9, respectively. Then, amplification (7 PCR cycles) of the resulting library was performed. During this process, the adapter sequences were completed and index sequences were added to them. NEBNext Multiplex Oligos for Illumina (Dual Index Primer Set 1) and NEB Next MultiplexOligos for Illuminia (DualIndex Primerset 2) regents were used for indexing. Qualitative evaluation of the obtained libraries was done using Agilent Bioanalyzer 4150 TapeStation High Sensitivity D5000ScreenTape and D50Kits. Quantitative evaluation was done by real-time PCR using Kapa Library Quantification Kits (Kapa Biosystems). The resulting metagenomics libraries were mixed equally into a pool and sequenced on Illumina NovaSeq600.