It wasn't very long ago when much of the DNA found in prokaryotes and eukaryotes was considered "junk DNA" because it did not directly code for a protein. We now know that DNA doesn't have to just code for a protein to have a function.  This is particularly true of the controlling mechanisms of transcription. But the importance of this discovery can easily be overlooked as just information that you need to know for a test. In what ways do you think information about gene expression in bacteria is valuable? This is an open-ended question and feel free to interpret in your own way.