Negative control for E. coli sxy experiments

I'm still planning the experiments to identify conditions that induce sxy expression (and possibly competence) in E. coli.

One issue I hadn't considered previously is the appropriate negative controls. If I'm using the sxy-inducible ppdD::lacZ fusion to indicate sxy expression, the best control will be a sxy-knockout mutant carrying the same lacZ fusion. We might already have such a mutant (from the wonderful Japanese group that provides clones and knockouts of E. coli genes), but if not I'll need to make one. This would be best done using the genetic technique called recombineering, which one of the post-docs has been trying to get working for us. I'll start working with her on this.