Effect of biofilm by plant probiotic rhizobacteria on root colonization and growth of wheat

A total of 11 probiotic strains of Bacillus subtilis were used to evaluate the potential of biofilm formation and wheat root colonization. Experiments carried out in a completely randomized design with four replications. According to results of this study, biofilm formation and biosurfactants production showed a high diversity in studied rhizobacteria, B3, B1 and B4 strains produced the maximum amount of mentioned metabolites. Evaluation of root colonization was performed using rifampicin and nalidixic acid resistant mutants. B4 and B3 with 4.41×107 cfu/gand 4.35×107 cfu/g had the highest root colonization compared to other strains. Correlation of 0.74 and 0.80 was obtained between biofilm formation and biosurfactants production with wheat root colonization, respectively. In another part of this study, the effects of studied strains were evaluated on wheat plant growth factors. All probiotic rhizobacteria strains increased the length of roots and aerial part of wheat and most of them increased dry weight of roots and aerial part. Based on the findings of this research, strains with high potential in biofilm formation and biosurfactants production were colonized wheat root very well and most of studied strains showed the effect of increasing on wheat growth factors.