FIG. 1.

Presence of plasmid-borne rrnB (pNO1301) is detrimental to cell growth in rich media. (A) Heterogeneous colony sizes for cells transformed with plasmid pNO1301 compared to cells transformed with plasmid pBR322 on LB medium plates containing ampicillin. The arrow indicates a representative big colony that emerged in the otherwise small-colony background. A representative small colony is indicated by an arrowhead. (B) Growth curves for big and small transformants with plasmid pNO1301. For comparison, the growth curve for a transformant with pBR322 is included. Growth was monitored in cultures grown in LB medium containing ampicillin at 37°C. O.D. 600 nm, optical density at 600 nm.