A SIMPLE SINGLE-CELL TECHNIQUE FOR GENETIC STUDIES OF BACTERIA

Abstract

Numerous techniques have been described for the propagation of bacterial cultures from individual cells. (See Hildebrand, 1950, for a review.) Although isolation of single cells may result in genetic homogeneity in the few generations immediately following their isolation, spontaneous mutations almost certainly destroy this homogeneity upon continued cultivation. Consequently, the de-scription of another technique for obtaining such single-cell cultures would serve little purpose. The present paper describes an extension of the usual tech-niques that makes possible critical genetic studies when applied to suitable material. This extension consists of the isolation of a number of single-cell cul-tures of known relationships descending from one original cell. SINGLE-CELL ISOLATION TECHNIQUE A film of agar is prepared by spreading about 0.05 ml of melted 2 per cent agar with a heated, 0.1-ml graduated pipette over the central portion of a 22-by-50-mm no. 1 cover slip. The cover slip is inverted over a moist chamber of about 10-mm depth, which is closed at one end and contains strips of wet blotting