Isolation of infective and effective Frankia strains from root nodules of Alnus acuminata (Betulaceae)

CARU, M., A. BECERRA, D. SEPULVEDA & A. CABELLO

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY

Kluwer Academia Publishers

Lugar: Netherlands; Año: 2000 vol. 16 p. 647 - 651

0959-3993

Two Frankia strains were isolated from root nodules of Alnus acuminata collected in the Tucumano-oranense forest, Argentina. Monosporal cultures were obtained by plating a spore suspension of each strain and isolating a single colony. The strains (AacI and AacIII) showed branched mycelia with polymorphic sporangia and NIR-vesicles. They differed in their ability to use carbon sources: the AacI stain grew well on pyruvate, while the AacIII strain grew on mineral medium supplemented with glucose or, alternatively, with sucrose. The two strains were sensitive to oleandomycin, eriythromycin, kanamycin, penicillin G, streptomycin and vancomycin. The nitrogenase activity in vitro of the strains was significantly higher in basal medium without nitrogen than that determined in the presence of ammonium chloride. Both strains were infective on seedlings of Alnus glutinosa, inducing an approximately similar percentage of nodulated plants (80%), although strain AacIII produced a higher number of nodules per plant (less or equal than 15) than strain AacI (less or equal than 6). They were also effective for nitrogen fixation in planta, determined by acetylene reduction assay.