In prokaryotes, the 16S ribosomal RNA sequence has become a standard molecular marker for the description of a new species. While these marker sequences have become widely used, the quality of the sequence data and the associated meta-data being submitted to INSDC databases varies considerably. Recognizing the importance of access to high quality data for these markers, NCBI has expanded its targeted loci project to provide an up-to-date source of curated data. The targeted loci project currently maintains nearly 18 000 16S ribosomal RNA reference sequences of which over 95% are from type strains. The type strains are considered the exemplar of the species and it is essential that type strain data be annotated with correct metadata and be free from contamination.
