PGPR characteristics of rhizospheric bacteria to understand the mechanisms of bean growth

Rhizobacteria play an important role in maintaining soil balance, among these bacteria there are those which have shown their ability to promote the growth of plants known as Plant Growth Promoting Rhizobacteria (PGPR). In our work, we are interested in characterizing 110 bacterial strains isolated in the field in the region of ben badis (Constantine Algeria) from 5 varieties of bean. Phenotypic and biochemical characterization showed that most of the isolates are cream colored, slightly raised, flat and opaque, gram-, catalase + and oxidase-, Bacillus form. PCA analysis allowed us to select 40 isolates with a high degree of variability to continue our work. The results obtained have directed us towards different taxonomic groups (rhizobium, Pseudomonas, bacillus etc.). The evaluation of the PGPR potential of bacteria (phytostimulation, biofertilization and biocontrol), showed that 100 % of bacteria are able to produce auxin at different concentrations with the highest concentration (177.77µg / ml) for the isolate 6, that more than 50% of isolates are capable of producing nitrogen, ammonia and phytate mineralization. These PGPR traits are a direct effect on plant growth of five varieties of the bean and can be used to select the best performing bacteria for inoculation tests.