New Stage in E.Coli Growth

ABSTRACT

The kinetics of growth of Escherichia coli K12 in standard medium LB supplemented with 1% glucose is studied by measuring the optical density, the electric polarizability and the size of bacteria. The electro-optical method of Electric Turbidimetry, based on the change in the optical density at orientation of cells in electric field, is used. We found out that there is an additional stage after the exponential phase and before the stationary phase. This intermediate stage has longer duration than that of the exponential phase and is different from the so-called early stationary phase. This new stage, which has not been described by now, is characterized by linear increase in the optical density, twice decrease in the electric polarizability and oscillations of the average bacteria size.

Keyword:

• culture growth
• E. coli K12
• electro-optics
• electric polarizability
• length growth