Several works discuss about which housekeeping genes are more suitable to be used as endogenous references for normalization in eukaryotes. However, to my best knowledge, no similar comparisons have been performed for E. coli reference genes. I searched in PubMed several works where qRT-PCR was used to measure gene expression in E. coli, and the most used housekeeping genes are:

rrsG (16S ribosomal RNA)

arcA (Aerobic respiration control)

rpoA (RNA polymerase)

However, no validation experiments showing the reliability of those genes as "stable expression references" were performed in the vast majority of the studies.

As robust relative expression calculations require considering several control gene references, I`m looking for other genes that people have used for this purpose in E. coli (or related species) gene expression studies. Please share your experience!