FIG. 3.

Effect of electric field strength on the electrotransformation efficiency of B. fragilis strain NCTC9343 with pLYL05. B. fragilis strain NCTC9343 competent cells prepared from 48-h cultures were electroporated with 1.0 μg pLYL05 DNA at the electric field strengths indicated. After 3 h of postpulse incubation, cells were spread onto GAM agar plates containing 50 μg/ml Cfx. Transformant colonies were counted after 48 h of anaerobic cultivation at 37°C. The open and filled circles indicate the log₁₀ numbers of viable cells/ml of culture and log₁₀ numbers of transformants/μg pLYL05, respectively.