Fundamentals of Microbiology

2.5.5 Synchronous culture

Synchronous culture is composed of cells which are at the same stage of cell cycle. Synchronous culture of bacteria can be obtained by several techniques. Synchrony in bacteria is accomplished either by repetitive shifts of temperature or by furnishing fresh nutrients to cultures that have just entered the stationary phase.

A synchronous population can be selected from a random population by physical separation of cells that are at the same stage of development. An excellent method of obtaining synchronous culture is the Helmstetter – Cummings technique – which is based on the fact that certain bacteria stick tightly to cellulose nitrate filter. This technique involves filtering an unsynchronized culture of bacteria through filter, then inverting the filter and allowing fresh medium to flow through it. After loosely associated bacteria have been washed from the filter, the only bacterial cultures in the effluent stream of medium are those which arise through division. Hence all cells in the effluent are newly formed and at the same stage of cell cycle.

Synchronous cultures rapidly lose synchrony because various cells of a population do not divide at the same size, time.