What is the difference between "root" and "cellular organisms" in NCBI taxonomy?

Question

[luise.schulte]

Hi all,

I classified a shotgun sequenced environmental DNA sample using kraken2. I get most of my sequences (apart from unclassified) classified as "root" and as "cellular organisms". Now I tried to find out what the difference is in the NCBI taxonomy but I find nowhere an explanation. Does anybody know the difference? Isn't "cellular organism" already including all life on the plant? So what on earth can "root" be?

Thanks for any ideas!

Here the top of my kraken report:

  99.62  59175599        59175599        U       0         unclassified
  0.38   227134          16942           R       1         root
  0.35   209708          14266           R1      131567    cellular organisms

Answer 1

[Pierre Lindenbaum]

root includes viruses. https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi

[luise.schulte]

Ahh, how stupid of me not to think of viruses :P Thanks a lot!