Bacterial Strains and Growth Conditions—The wild-type X.
campestris pv. campestris strain Xc1 has been described previously
(20). The Xc1 derivatives carrying various mutations or
constructs were described in Figs. 1–5. X. campestris pv.
campestris strains were grown at 30 °C in YEB medium (22),
unless otherwise stated. E. coli strains were grown at 37 °C in LB
medium. Antibiotics were added at the following concentrations
when required: 100 g/ml kanamycin, 50 g/ml rifampicin,
and 15 g/ml tetracycline; X-gluc (5-bromo-4-chloro-3-
indolyl-D-glucopyranoside) was included in the medium at 60
g/ml for the detection of GUS (-glucuronidase) activity. DSF
signal was added to the medium in a final concentration of 3M
when necessary.