Merging qiime2 sample metadata with exterior taxonomic classifications

Hello! I am relatively new to bioinformatics, and qiime 2 especially, so bear with me and let me know if anything needs clarified or corrected!

I am working on diet metabarcoding analyses (arthropods eaten by dragonflies), and have already trimmed and denoised my samples in q2. I am trying to add features (with taxonomic IDS) per sample to each sample row of a metadata file. Essentially, my goal is to create a table which outlines what taxa were eaten by each individual, which would be really great for downstream analyses.
I have tried taxonomic classification within q2, using a pre-existing classifier, but have found that the BOLD COI barcode ID tool returns more detailed results for the same representative sequences, which would make comparisons more meaningful. I have seen that it is possible to train a qiime classifier on the BOLD database, but I have a heavy time constraint, so I am seeing if there are alternatives before taking that labor on.

Because my BOLD classifications are saved to the same feature IDs created by the DADA2 denoising process, I am wondering if it would be possible to obtain the feature IDS attributed to each sample in the feature table artifact I currently have, to "match them up" (probably outside of qiime2) with their associated taxon from the BOLD output. Based on the feature table visualization, it seems like qiime 2 is storing the feature information for each sample, but I'm not sure if or how to access it prior to in-house taxonomic classification.

Is this feasible, and if so, how can I go about it? Thank you so much, and apologies if there are any issues with the forum post.

Hello Randall,

Welcome to the forums! :qiime2:

You may find this thread interesting!


The easiest way to get a plain-text version of your feature table is to first export the artifact, then convert the resulting BIOM table.

qiime tools export \
  --input-path your-feature-table.qza \
  --output-path exported-feature-table
biom convert \
  -i exported-feature-table/feature-table.biom \
  -o feature-table.tsv \
  --to-tsv

There are a few ways to do this within Qiime2 too, if you would prefer.