On the origin of branches in Escherichia coli

Some Escherichia coli strains,vith impaired cell division form branched cel ls at high frequencies during certain growth conditions, Here, we show that neither FtsI nor FtsZ activity is required for the development of branches . Buds did not form at specific positions along the cell surface during hig h-branching conditions. Antibiotics affecting cell wall synthesis had a pos itive effect on branch formation in the case of ampicillin, cephalexin, and penicillin G, whereas mecillinam and D-cycloserine had no substantial effe ct. Altering the cell morphology by nutritional shifts showed that changes in morphology preceded branching, indicating that the cell's physiological state rather than specific medium components induced branching. Finally, th ere was no increased probability for bud formation in the daughters of a ce ll with a bud or branch, showing that bud formation is a random event, We s uggest that branch formation is caused by abnormalities in cell wall elonga tion rather than by aberrant cell division events.