FIG. 4.

Cultural characteristics of the oxidase-deficient mutants. Cultures were grown in BHI broth under aerobic conditions in the presence (solid lines) or absence (dotted lines) of exogenous catalase. (A) SpxB-defective mutant HT1; (B) Lox-defective mutant HT2. Upper panels show cell growth in terms of cell mass (•) and cell viability (⧫); lower panels show glucose consumption (▴) and H₂O₂ (▪). Representative results of at least five independent experiments are shown. (C) Comparison of the final levels of cell mass achieved by the wild type (•), the SpxB-defective mutant HT1 (▴), and the Lox-defective mutant HT2 (▪). Means ± the standard deviations for three independent experiments are shown.