Plant Growth Promoting Rhizobacteria (PGPR) play an important role in agricultural systems, especially
as biofertilizer. The objectives of this study were to select effective PGPR for forage corn (Zea mays L.)
cultivation and to investigate the effect of their inoculation on indigenous microbial community structure.
The putative genera Pseudomonas sp. SUT 19 and Brevibacillus sp. SUT 47 were selected for determining
their efficiency in forage corn growth promotion in both pot and field experiments. In field
experiment, PGPR amended with compost gave the highest results in comparison to all treatments.
Denaturing Gradient Gel Electrophoresis (DGGE) fingerprints of 16S rDNA amplified from total
community DNA from rhizosphere confirmed that our isolates existed in rhizosphere throughout this
study. The microbial community structures were slightly different among all treatments whereas major
changes depended on stages of plant growth. In order to evaluate whether PGPR have effect on species
diversity in rhizosphere, DNA sequencing of excised DGGE bands was done. The results demonstrated
that dominant species in microbial community structure were not interfered by PGPR, but strongly
influenced by plant development.