It is now recognized that sRNAs originate from various loci as sense or antisense, including IGR, 3’ and 5’ ends of transcripts and CDS. We investigate the functions and the mechanisms by which sRNA regulators influence Salmonella’s metabolism and/or virulence. Traditionally, the study of the functions of these sRNAs required a laborious examination of the sRNAs one by one by over-expression. Recently we developed a new tool in the form of an expression library of many sRNAs which when subjected stress enables the identification and/or selection of functional sRNAs in an unbiased manner.