[Resistance to antibiotics in strains of Azospirillum sp]

A total of 32 strains of Azospirillum mainly isolated from rhizosphere of grasses and soils of Argentina were examined for susceptibility to 9 antimicrobial agents (trimethoprim, ampicillin, carbenicillin, streptomycin, spectinomycin, chloramphenicol, kanamycin, nalidixic acid and tetracycline). Many of the strains were sensitive to tetracycline, kanamycin, chloramphenicol and nalidixic acid, and resistant to ampicillin (more than 50 mg/l) and carbenicillin (more than 200 mg/l). In spite of this general pattern, for most of the strains it was possible to obtain an antibiotype. Such antibiotype could be useful for identification of the strains in field experiments or in genetic transfer experiments.