Isolation and Characterization of Indole-3-butyric Acid-producing Azospirillum Bacteria from Grapevine Rhizosphere

Ten isolates of Azospirillum bacteria named from Azo-1 to Azo-10 have been isolated from the grapevine rhizosphere. Azospirillum isolates in Dobereiner medium with 0.01% tryptophan were evaluated for their ability to produce Indole-3-butyric acid (IBA). Indole butyric acid (IBA) was determined by colorimetric Salkowski reaction. As a result, of ten Azospirillum isolates collected from grapevine rhizosphere 3 isolates (30%) bio-synthesized IBA below 9 μg/mL, 5 isolates (50%) produced IBA from 9 to 17 μg/mL, and 2 isolates (20%) were recorded this value from 22 to 29 μg/mL. The results show a great variation among the tested Azospirillum isolates in production capacities of IBA (from 5 to 29 μg/mL). The results also show that the isolate Azo-4 produced the highest amounts of IBA (29 μg/mL). The highest five of Azospirillum isolates (Azo-1, Azo-4, Azo-6, Azo-8 and Azo-9), which are capable of producing IBA (22, 29, 15, 14 and 17 μg/ ml, respectively), are identified by the cell morphological, physiological and biochemical characteristics. Based on all the identification characteristics, select isolates were identified as Azospirillum spp.