Waterside W25, Liverpool outdoor environment
Environmental swabs preserved in DNA/RNA Shield were shipped at ambient temperature to MicrobesNG (Birmingham, UK) for DNA extraction, Illumina library preparation, and shotgun metagenomic sequencing. Libraries were prepared using the Illumina Nextera XT kit with modified input and PCR conditions. Libraries were sequenced using 2  250 bp paired-end reads with a target yield of 2 million reads per sample. Reads were quality-trimmed using Trimmomatic v0.39 and assessed using fastp v0.23.2 and internal MicrobesNG QC tools. Samples with <500,000 read pairs or with an overlapping insert-size peak deviating from ~400 bp were removed prior to downstream analysis.