Division planes alternate in spherical cells of Escherichia coli

Abstract

In the spherical cells of Escherichia coli rodA mutants, division is initiated at a single point, from which a furrow extends progressively around the cell. Using "giant" rodA ftsA cells, we confirmed that each new division furrow is initiated at the midpoint of the previous division plane and runs perpendicular to it.

FIG. 1

Single cell of strain KJB28 [rodA(Am) ftsA.12(Ts) Sup⁰] dividing on NB agar at 30°C, following 90 min of growth at 42°C without division. Photographs were taken at 10-min intervals as indicated by numbers next to the frames.

FIG. 2

Successive divisions of a KJB28 cell on NB agar at 30°C, following 90 min of growth at 42°C without division. Photographs were taken at 10-min intervals as indicated by numbers next to the frames.

FIG. 3

Proposed explanation for the appearance of chains of KJB24 cells after growth in Methocel. (A) On NB agar, cells are prevented from moving as they divide so that alternating planes of cell division give rise to tetrads. (B) In Methocel, cells are held less firmly in place so that as the division furrow progresses from one side, the cells fall apart. New division furrows are initiated in the middle of the completed division planes and appear to be parallel or nearly parallel to the first division plane. The process repeats to give a kinked chain of cells (or, sometimes, an irregular clump).