Physiological properties and plasmid content of several strains of Azospirillum brasilense and A. lipoferum

Abstract

Four strains of Azospirillum brasilense, including strain 7000 (ATCC 29145) and five strains of A. lipoferum, including strain Br17 (ATCC 29709) were examined for the presence of plasmids. All the strains were found to harbour 1 to 5 plasmids whose molecular weight ranged from 3.5 to over 300 Md. No obvious relationship between the plasmids and phenotypic properties was established as yet, in particular N2 fixation, substrate utilization, drug resistance and lysogenic state. Six out of the 9 strains were lysogenic and phage production was inducible by mitomycin C. An icosahedric phage was purified from strain 7000.