Unmasked β-galactosidase activity as an indicator of membrane leakiness and cell lysis. The data present percentage of β-galactosidase activity, measured from non-permeabilized cells against total enzyme activity determined from permeabilized bacteria. Results for P. putida PaW85 (wt), colR-deficient (colR), ttgC-deficient (ttgC) and colRttgC double mutant (colRttgC) strains are shown. Bacteria were grown overnight on solid glucose M9 minimal medium (glc) or on the same medium supplemented with 1 mM phenol (glc+phe). Data (mean ± standard deviation) of at least three independent determinations are presented.