Nodulation Competitiveness of Ensifer meliloti Alfalfa Nodule Isolates
and Their Potential for Application as Inoculants
Monika Marek-Kozaczuk, Jerzy Wielbo, Anna Pawlik, Anna Skorupska Pol J Microbiol 2014; 63 (4): ICID: 1130747 Article type: Original article IC™ Value: 10.00
Abstract provided by Publisher
Alfalfa (Medicago sativa) is widely cultivated legume, which enters into nitrogen-fixing symbiosis with Ensifer (Sinorhizobium) spp. In this study, autochthonous rhizobial population of Ensifer sp. occupying alfalfa nodules grown in arable soil was used as the basis for selection of the potential inoculants. Alfalfa nodule isolates were identified as Ensifer meliloti by partial 16S rDNA, recA, atpD and nodC nucleotide sequencing. The sampled isolates have shown different symbiotic performance and diversity in plasmids number and molecular weight. The isolates most efficient in the symbiotic nitrogen fixation were tagged with a constitutively expressed gusA gene carried by a stable plasmid vector pJBA21Tc and used in competition experiments in soil under greenhouse conditions. Two E. meliloti strains LU09 and LU12, which effectively competed with indigenous soil rhizobia, were selected. The metabolic profiles of these selected strains showed the differences in the use of carbon and energy sources. In addition, the LU09 strains revealed bacteriocin production and LU12 mineral phosphate solubilization, which are valuable traits for soil survival. These strains may be considered as potential biofertilizers for alfalfa cultivation.