Bacillus paralicheniformis 2R5 and its impact on canola growth and N-cycle genes in the rhizosphere.

Chemical fertilization has a negative impact on natural environment. Plant growth-promoting (PGP) rhizobacterial biofertilizers can be a safer alternative to synthetic agrochemicals. In this research, a culture-based method was used to assess the population size of rhizobacteria at the vegetative, flowering, and maturity stages of canola. Rhizobacteria were then isolated from each of the canola growth stages, and their seven PGP traits were determined. The highest abundance of culturable bacteria was found at vegetative stage of the plants. Furthermore, four out of seven PGP traits were produced by the highest % of isolates at vegetative stage. In the greenhouse experiment that included six rhizobacterial strains with best PGP traits, the greatest canola growth promotion ability under sterile conditions was observed after the introduction of Bacillus paralicheniformis 2R5. Moreover, under non-sterile conditions, 2R5 significantly increased canola growth. The presence of trpA, B, C, D, E, F and pstA, S genes in the 2R5 genome could be associated with canola growth promotion abilities. chiA and mbtH genes could contribute to 2R5 antifungal activity against fungal pathogens. Moreover, the introduction of 2R5 significantly increased the abundance of narG, nosZ, nifH, and nirS genes, which can prove that 2R5 strain may be an important member of soil bacterial community.