Fig. 2. Growth and cell morphology of planktonically growing cells.

a, g Growth curves of WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A) cells grown planktonically in Middlebrook 7H9 (a) or LB (g) medium. OD₆₀₀, optical density at 600 nm. Error bars represent the standard error of the mean of three biological replicates. b, h Doubling times, determined from optical density growth curves, of WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A) cells in 7H9 (b) or LB (h) during log-phase growth. The middle line indicates the mean of three biological replicates (indicated with colored squares). The bottom and top lines represent the standard error of the mean. c, i CFU/mL of WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A) cells in 7H9 (c) or LB (i) at the 24-h timepoint. The middle line indicates the mean of 3 biological replicates (indicated with colored squares). The bottom and top lines represent the standard error of the mean. d, j Phase contrast micrographs and cell width profiles of planktonic WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A) cells grown in 7H9 (d) and LB (j). Each cell’s length was normalized to the same length with “p” and “m” indicating cell poles and mid-cell, respectively. The percentage values above the dotted colored lines indicate the portion of cells exhibiting maximum cell widths greater than or equal to the corresponding cell width threshold. e, k Boxplots comparing the distribution of maximum cell widths between WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A) strains grown planktonically in 7H9 (e) or LB (k). n = 100 cells for each strain in panel (e) and n = 92, 94, 100, 100 cells for WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A), respectively in panel (k). f, l Boxplots comparing the distribution of cell lengths between WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A) strains grown planktonically in 7H9 (f) or LB (l). The boxplots are drawn as described in Fig. 1. Statistical significance for each experiment was determined by one-way ANOVA and Tukey post-hoc test. n = 174, 162, 111, 136 cells for WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A) respectively in panel (f). n = 92, 94, 121, 158 cells for WT, ∆mptA, ∆mptA L5::mptA (WT), and ∆mptA L5::mptA (D129A), respectively in panel (l). Source data for each sub-panel are provided in the Source Data file. Microscopy image data for panels d–f, j–l are available at https://github.com/IanLairdSparks/Sparks_2023.