FIGURE 2.

Acidic pH alleviates cell separation defect of amidase mutants. Representative micrographs of double [ΔamiAB (EAM1379), ΔamiAC (EAM927), and ΔamiBC (EAM1381)] and triple amidase (ΔamiABC, EAM1385) mutants during steady-state growth in LB medium buffered to pH 6.9 or 5.2 compared with the parental strain (MG1655). Cells were grown to mid-exponential phase (OD₆₀₀ ~ 0.2–0.6) at the indicated pH, sub-cultured into the same medium at an OD₆₀₀ ~ 0.005, then sampled and fixed at OD₆₀₀ ~ 0.1–0.2 for microscopy. Scale bar denotes 20 μm. Quantification for each mutant is shown below the corresponding set of micrographs. Points indicate individual chain length measurements from at least two independent experiments, and error bars denote standard deviation. Y-axis gradient emphasizes the difference in scale used between mutants. Significance was determined by Kolmogorov–Smirnov test with a threshold of statistical significance set to p < .01