Accession numbers for reference sequences used in Kraken database build

This is a metadata file containing all the reference sequence accession numbers used to construct the custom Kraken 2 database in the paper “Airborne eDNA captures three decades of ecosystem biodiversity”. The file is the seqid2taxid.map file output by Kraken 2 during the database build process and maps the sequence accessions to their corresponding taxonomic identifiers (TaxID). Accessions of the form “kraken:taxid|TaxID|ACCESSION” are custom substrings added to the fasta headers of sequences not present in the “nucl_gb.accession2taxid” and “nucl_wgs.accession2taxid” files (both part of the NCBI taxonomy) that Kraken searches to get the TaxID mappings of the input sequences – to allow Kraken to match these sequences to the correct TaxID. Sequence accessions can be retrieved from the last part of that substring. The file is approximately 24 Gb in decompressed form and contains ~700 million accessions.