| Method |
P.2 right column 2nd & 3rd paragraphs: "Strain MW162 of E. coli K-12 [ref 18] was grown either in LB medium or in M9 minimal salt medium supplemented with 0.4% glucose, both with ampicilin (100 µg/ml). Bacteria were cultivated at 37 °C with vigorous shaking up to OD600 = 0.2 in the exponential growth regime. In calibration experiments, the cytoplasmic membrane (CM) was stained with 1 µM FM4-64 (Molecular Probes) after fixation with 0.2% formaldehyde. For microscopy, researchers apply 10 µl of exponential bacterial culture on a thin layer of 1.5% agar with LB (Sigma) or prepared on the M9-glucose medium. Measurements start only after one division is completed and [researchers] avoid analyzing cells that are too far along the division process at the start of the experiment. As a result, data are collected no less that 10 min after the cells are shifted to agar for fast-growing conditions (LB) and no less than 20 min for slow-growing cells (M9-glucose). Growth of individual bacteria (a total of 30) was monitored during at least two cell cycles. [They] have verified that cells grow at a steady state on the agar. This was done by monitoring about nine generations of a micro-colony originating from a single-cell, and counting the number of cells, N, as a function of time (data not shown)." |
| Comments |
P.2 right column 3rd paragraph:"[Researchers] find that up to five generations, the growth of N is exponential. In LB, the average doubling time for the 30 cells was 18.10 ± 0.52 min which is consistent with the generation time measured by monitoring OD600 of the corresponding liquid culture, 22.27 ± 0.69 min. The corresponding times for cells grown in M9-glucose were 38.38 ± 1.10 min and 48.64 ± 1.61 min, respectively. Although the difference between the generation times is significant (about 20% for both LB and M9-glucose), the faster growth rate on agar indicates that the solid support does not restrict cell growth." P.4 right column 3rd paragraph: "The growth rate at t > τc [time when division starts], a2, is due both to that of the cylinder, a1, and that of the new poles, ah, and therefore [researchers] expect that a2 = a1 + 2ah." Initial cell length, L0, is 2.482 µm. Length at end of generation time, L(τg), is 5.034 µm. See BNID 100002, 103714, 104113, 104825, 102065, 100001 |