WNK1 and infection: To gain more insight about the mechanism of comK induction in response to oxidative stress, a collection of knock-out mutants for regulators known to respond to H2O2 and related infection signals (rswB, codY, ccpA, ccpE, rot, sarA, kdp, phoR, agrCA, srrAB, arl and saeRS) was then tested to determine whether any showed reduced induction of comK expression in response to H2O2 (Supplementary Fig. 6A).