Genome of E. coli with ribosomal RNA and tRNA genes highlighted--courtesy

Last update:

version 4.4.4

(see About rrnDB Versions for changes)


A searchable database documenting variation in ribosomal RNA operons (rrn) in Bacteria and Archaea. Find information such as the 16S gene copy number of an organism by looking up its name under the NCBI or RDP taxonomy or by full-text search of rrnDB's records.

Please cite the use of rrnDB in the following way:

This article is freely available as abstract and full text [HTML] [PDF].

Curated by the Schmidt Laboratory at the University of Michigan.

Search the database
Estimate the number of rrn operons
Learn more about rrnDB
Cite the rrnDB's NAR article

The current rrnDB version (4.4.4) includes 2,865 Bacterial records representing 1,462 species, and 180 Archaeal records representing 153 species.