See also
search_16s command
Bit vector files are created by the udb2bitvec command . The recommended sequence database is the Greengenes 97% representative set . You should use the -wordlength 13 option of makeudb_usearch to create the udb file, as shown below.
usearch -makeudb_usearch gg97.fa -wordlength 13 -output gg97.udb
usearch -udb2bitvec gg97.udb -output gg97.bitvec