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

Latest release:

version 4.3.3

(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 (4.3.3) includes 2,635 Bacterial records representing 1,383 species, and 175 Archaeal records representing 148 species.