Efficient transformation of pseudomonas strains with pNI vectors by electroporation.

The optimum conditions for electro-transformation of some Pseudomonas strains including P. putida, P. fluorescens, and P. flavida, were defined using the pNI105 vector, resulting in 100-10,000 fold increases in transformation efficiency compared with conventional chemical transformation with MgCl2. The growth phase of the cultured cells and the field strength were important in obtaining high transformation efficiency. Under optimal conditions, 3.2 x 10(7) transformants per 1 microgram DNA were obtained using a combination of pNI105 and P. fluorescens IAM12022. This value is the highest ever obtained for a Pseudomonas species. In addition, the procedures were applicable to the effective transformation of fluorescent Pseudomonas strains with pNI vectors.