Isolation and identification of the most efficient plant growth-promoting bacteria associated with canola (Brassica napus)

Thirteen of the most abundant Gram-negative bacteria which are able to grow in N-depleted culture conditions were isolated from the rhizoplane and endorhizosphere of canola (Brassica napus) and identified by 16S rDNA sequence analysis. Eight of these bacteria induced a significant increase in root dry weight ranging from 11 to 52%. Phylogenetic positioning based on 16S rDNA sequences indicated that at least four genera are represented, Pseudomonas, Vario-vorax, Agrobacterium and Phyllobacterium, The most important direct plant growth-promoting-rhizobacteria effect was found with both isolates belonging to the Phyllobacterium.