The genome quality assessment (GC content, and completeness and contamination estimates) is from GTDB (release 214). Coverage was determined by mapping trimmed metagenomic reads to a dereplicated set of MAGs generated from groundwater samples, including nzgw271, using bowtie2 v2.3.2 (-n 1 -l 222 –minins 200 –maxins 800 –best). Reads were trimmed by first removing adapters using cutadapt, and then trimmed low quality bases with sickle (Phred score >= 30; length >=80 bp).