I would like to announce to the QIIME community the launch of a new 16S database for taxonomic assignment compatible with QIIME.
MIMt is composed of 16S sequences from species well identified and curated from RefSeq. All 16S sequences were extracted from sequenced genomes and not from isolated sequences deposited in the public databases reducing the chances of misclassification.
As the source of the database is the species genome, it contains only one "representative" by species with all its 16S copies, but there are no sequences belonging to the same species from different isolates, strains or metagenomes.
MIMt is very compact but very powerful in taxonomic assignment even at species level since every sequence has full taxonomy classification.
You can download MIMt from https://mimt.bu.biopolis.pt
Therefore, NCBI itself places no restrictions on the use or distribution of the data contained therein. Nor do we accept data when the submitter has requested restrictions on reuse or redistribution. However, some submitters of the original data (or the country of origin of such data) may claim patent, copyright, or other intellectual property rights in all or a portion of the data (that has been submitted).
Choosing a license provides clarity to users like me about how a database can be used.
(I would not use a database if I did not know its license.)