TRANSFER OF THE BROAD-HOST-RANGE INCQ PLASMID RSF1010 AND OTHER PLASMID VECTORS TO THE GRAM-POSITIVE METHYLOTROPH BREVIBACTERIUM-METHYLICUMBY ELECTROTRANSFORMATION

Gram-positive facultative methylotrophic coryneform bacterium Brevibac terium methylicum was efficiently transformed with various plasmids us ing electroporation of intact cells. In addition to the plasmid vector s pEC71 and pZ6-1 constructed on the basis of cryptic plasmids from co ryneform bacteria, broad-host-range plasmids pLS5 (derivative of plasm id pMV158 from Streptococcus agalactiae) and RSF1010 belonging to the incompatibility group IncQ from Gram-negative bacteria were found to b e present as autonomous structurally unchanged DNA molecules in B. met hylicum transformants. With the exception of pZ6-1, all these plasmids were stably maintained in B. methylicum cells grown under non-selecti ve conditions. When plasmid DNAs isolated from B. methylicum were used , the highest efficiency of transformation (10(5) transformants/mu g D NA) was achieved.