[Plasmid content in strains of Azospirillum sp]

In this work, the plasmid content of 22 strains of A. brasilense and 7 of A. lipoferum, isolated from different regions of Argentina was analyzed. Of the several methods for the extraction of plasmids, a modification of that of Kado and Liu was found to be the most appropriate for the isolation of a larger number of high molecular weight plasmids. Out of 29 strains analyzed, 26 were found to contain between one and four plasmids, all of them of high molecular weight (Figure 3, Table 1); 44% of the plasmid-containing strains showed one large plasmid of similar electrophoretic mobility and of approximately 100 Mdal.