Biochemical and Molecular Identification of Azospirillum brasilense Bacteria and Evaluation of Their Efficiency in Producing Hormones, Dissolving Phosphorus, and Fixing Nitrogen

The study aimed to isolate A.brasilense bacteria from the soil of the rhizosphere of different plants and different locations in Al-Diwaniyah Governorate. They were identified in two ways. The first was the routine method, which included studying the microscopic and cultural characteristics and biochemical tests of the isolates. The second method was molecular, using polymerase chain reaction (PCR) technology and using primers. It also included testing the efficiency of these isolates in dissolving tricalcium phosphate (TCP) on Pikovskaya agar medium, fixing nitrogen in the liquid nutrient medium (N.B), and measuring the amount of hormone production using an HPLC device. The results of isolation and regular and molecular identification the presence of ten isolates of bacteria bearing the characteristics of A. brasilense bacteria, out of fifteen local bacterial isolates, took the following symbols and sequences (Az2, Az3, Az5, Az6, Az7, Az9, Az11, Az12, Az13, Az14), as the results showed confirmation of the identification of the bacterial isolates identified by biochemical tests. Using a specialized primer to amplify the 462bp fragment of the 16S ribosomal RNA gene, the results of testing the efficiency of the bacteria in dissolving phosphate (TCP) showed that the isolate (Az13) outperformed the highest value in its effectiveness in dissolving metallic phosphorus through the diameter of the clear zone around the colony, which was effective in dissolving phosphate of up to 3.89 mm. As for the nitrogen fixation efficiency test, the isolate (Az3) excelled in the amount of fixed nitrogen reaching 12.44 mg.L-1. As for the amount of its production of growth regulators for Auxins, Gibberellins, and Cytokinins, the isolate (Az3) recorded the highest value in the amount of Auxins production ( Indol-3-acetic acid) its concentration reached 34.4 µg.ml-1, and as for the production of the hormone Gibberellins (GA3), the isolate (Az3) recorded the highest value amounting to 34.7 µg.ml-1, as for the production of the hormone Cytokinins (CK), The isolate (Az11) recorded the highest value, amounting to 28.8 µg.ml-1.