BLAST analysis of the sRNA sequences against the nonredundant, nucleotide database at NCBI revealed that 31 of the sRNA sequences were unique to the H. somni 2336 genome. Another 41 were highly conserved (.95% identity with .95% coverage) only in H. somni strain 129PT, which is a commensal, preputial isolate. A set of 11 sRNAs were conserved in the related Pasteurellaceae family, which includes genomes such as P. multocida, H. influenzae, H. parainfluenzae, and H. ovis. Only 11 sRNAs were conserved in distant bacterial genomes from genera Streptococcus, Clostrodium, Actinobacillus, Vibrio, and others. This lack of sRNA sequence conservation beyond the species could indicate that sRNA sequences are under strong selection pressure, and that they could be responsible for the adaptation of many species to different environmental niches.