Video talks on 16S data analysis posted.

URMAP ultra-fast read mapper posted (paper).

~20% of taxonomy annotations in SILVA and Greengenes are wrong (paper).

Taxonomy prediction is <50% accurate for 16S V4 sequences (paper).

97% OTU threshold is wrong for species, should be 99% for full-length 16S, 100% V4 (paper).

Dominant OTU

For a given OTU (call it X), a "dominant OTU" (call it D) is an OTU with much higher abundance and high sequence similarity. If X has a dominant OTU, then X may be a spurious OTU induced by bad sequences where the correct sequences belong in D.

This heuristic is similar to the method used by denoising algorithms to identify probable bad sequences; see UNOISE algorithm.

See Tolstoy's paradox for discussion of why bad sequences and spurious OTUs can be common even with very low error rates.