Identification of new SdiA regulon members of <i>Escherichia coli</i> , <i>Enterobacter cloacae</i> , and <i>Salmonella enterica</i> serovars Typhimurium and Typhi

Many bacterial species detect their own population density through the production, release, and detection of small molecules (quorum sensing). <i>Salmonella</i> and other Enterobacteriaceae have a modified system that detects the <i>N</i>-acyl-homoserine lactones of other bacteria through the solo quorum sensing receptor SdiA, a behavior known as eavesdropping. The roles of <i>sdiA</i>-dependent eavesdropping in the lifecycles of these bacteria are unknown. In this study, we identify <i>sdiA</i>-dependent transcriptional responses in two clinically relevant serovars of <i>Salmonella</i>, Typhimurium and Typhi, and note that their responses are partially conserved. We also demonstrate for the first time that <i>sdiA</i>-dependent regulation of genes is partially conserved in <i>Enterobacter cloacae</i> and <i>Escherichia coli</i> as well, indicating a degree of commonality in eavesdropping among the Enterobacteriaceae.