The makeudb_tax command creates a UDB database file
from sequences in a FASTA file. The database file
is compatible with the sintax,
usearch_local commands. Using a udb index
make the database faster to load, but otherwise does not change the results.
See SINTAX reference data downloads
page for available reference files.
You don't need to trim sequences to the same region as your reads / OTUs.
The sequence labels in the FASTA file must contain
usearch -makeudb_sintax rdp_16s.fa -output rdp_16s.udb