Effect of Phosphate Solubilizing Rhizobacteria on the Growth of Maize in the Seedling Stage

There is a great consideration on the usage of biofertilizers as the alternative for chemical fertilizers. Some species of Enterobacter are described to be used in biofertilizers with direct and indirect plant growth promotion. This research aims to isolate phosphate solubilizing bacteria (PSB) and evaluate their effects on maize growth. So, rhizobacteria were isolated from the maize rhizosphere, and screening was performed on Sperber and Zinc oxide media. Other rhizobacterial traits such as ammonia and hydrogen cyanide production, nitrogen fixation, nitrate reduction, and the effect of environmental factors were also evaluated. Out of 42 PSB, 5 isolated strains with the best results were used for further tests and they were identified based on their 16S rRNA gene sequence as Enterobacter cloacae, Enterobacter hermoche, and Enterobacter sp. All selected strains were able to solubilize phosphate and zinc and could tolerate NaCl up to 7% and grow in pH 5 to 9, and finally, they could grow in temperatures in a range of 4 to 44oC. All 5 isolates could significantly increase shoot height and root length, and wet weight of shoot and root. Finally, according to the in-vitro and in-vivo results, the evaluated capabilities of bacterial strains isolated from maize are attractive and highlighted and it makes them good candidates for the construction of novel biofertilizers.