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).

memory requirements for alignment

The amount of memory required to align a pair of sequences scales like the product of the sequence lengths. In the worst case, approximately 4NM bytes may be needed, where N and M are the sequence lengths. For very long sequences, say 20k or more, this can be a lot: 4 x 20k x 20k = 1.6 Gb.