Bacterial small RNAs (sRNA) are small RNAs produced by bacteria; they are 50- to 500-nucleotide non-coding RNA molecules, highly structured and containing several stem-loops. Numerous sRNAs have been identified using both computational analysis and laboratory-based techniques such as Northern blotting, microarrays and RNA-Seq in a number of bacterial species including Escherichia coli, the model pathogen Salmonella, the nitrogen-fixing alpha-proteobacterium Sinorhizobium meliloti, marine cyanobacteria, Francisella tularensis (the causative agent of tularaemia), Streptococcus pyogenes, and the plant pathogen Xanthomonas oryzae pathovar oryzae.