ELECTROTRANSFORMATION OF LACTOBACILLUS-PLANTARUM USING LINEARIZED PLASMID DNA

Evidence is presented that linearized plasmid DNA is capable of electr otransforming Lactobacillus plantarum at a frequency 500-fold lower th an with the covalently closed circular molecule. When the linearized p lasmid was religated prior to transformation the transformation effici ency was < 10-fold higher, suggesting that open circular plasmid was o nly slightly more efficient in the transformation of Lact. plantarum t han linear DNA. This observation has implications for direct cloning i nto this species since the high background transformation frequency pr oduced by the linear DNA could potentially obscure the recovery of clo nes. Nevertheless, using positive selection for enhanced chloramphenic ol resistance, cloned fragments of Lact. helveticus DNA were obtained using the shuttle vector pGKV110.