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).

Terminal and internal gaps

Terminal gaps
A terminal gap is an alignment gap which starts in the first column or ends in the last column. Local alignments never have terminal gaps.

Internal gaps
An internal gap is any gap that is not a terminal gap. Local alignments may have internal gaps.

Example
The global alignment below has terminal and internal gaps indicated. The -show_termgaps option was used for the -alnout output file. Note that the number of columns (302 in this example) is always reported without terminal gaps, as these are the columns used to calculate identity.