OPTIMIZATION OF THE TRANSFORMATION EFFICIENCY OF AGROBACTERIUM-TUMEFACIENS CELLS USING ELECTROPORATION

The procedure for electroporating the recombinant plasmid, pBI121, into Agrobacterium tumefaciens LBA4404 cells has been optimized. A 2-fold increase in the transformation efficiency of A. tumefaciens LBA4404 was observed using a 3-h expression period after electroporation compared to a 1-h expression period. The total number of viable cells remained similar using either a 1-h or a 3-h expression period. No significant difference in the transformation efficiency was shown using either one pulse or multiple pulses at field strengths of 8.9 kv/cm or 16.7 kv/cm. The transformation efficiency obtained by using AB broth, a well characterized medium for growing Agrobacterium cells, as the expression broth was similar to the efficiency using YM broth. Furthermore, using LB broth with 1% mannitol as the expression medium resulted in a transformation efficiency that was only slightly lower than the efficiency using YM broth. These results indicate that mannitol may have contributed to improving the transformation efficiency of A. tumefaciens cells after electroporation.