Not necessarily. The one bit of actual research I was able to do (in the late '70s) was in a lab that had serendipitously discovered a new iron scavenging mech

Not necessarily. The one bit of actual research I was able to do (in the late '70s) was in a lab that had serendipitously discovered a new iron scavenging mechanism in E. Coli. If you put it in a sufficiently iron poor environment (e.g. all the glassware was treated with HCL and then bathed for days in deionized water) it would synthesize a previously unknown iron binding protein and grab what it could. So we shouldn't assume this is the only way many bacteria can get iron, but it's perhaps worth checking out. And a focus on iron in general might be a fruitful approach.