Isolation and characterization of plant growth promoting bacteria from rhizosphere of Sophora alopecuroides

Plant growth promoting rhizobacteria (PGPRs) are a group of bacteria that enhance plant growth through direct and indirect effects. Isolation of PGPRs from Sophora alopecuroides rhizosphere and assessment of their plant growth promoting traits was the main aim of this study. Fifty two bacterial isolates were isolated from Sophora alopecuroides rhizosphere and their phenotypic and morphological characteristics were studied. Phosphate solubilization and production of ammonia, indole acetic acid, protease, lipase and HCN were evaluated in vitro.Phosphate solubilizing ability was assayed using PVK and NBRIP media. The results showed that the number of isolates with phosphate solubilization ability was 44 and 18 in those two media, respectively. The range of indole acetic acid production in isolates was 0.12 to 37 μg ml-1. The percentage of isolates which were capable to produce ammonia, protease, lipase and HCN were 83%, 87%, 87% and 65%, respectively. According to the results, three isolates (named as 20, 37 and 48) which showed positivereaction in phosphate solubilization, production of ammonia and indole acetic acid production tests, were introduced as the strains having capacity for using as biofertilizers. Two isolates (named as 13 and 43) with strong positive reaction in the tests of protease, lipase and HCN production; were regarded as potential candidates for using as biocontrol agents.The partial sequence of 16S rRNA gene of selected isolates was determined and the derived sequences were compared against the GenBank database using NCBI, BLASTN. Based on morphological and biochemical characters and also 16S rDNA sequence, some of isolates were belonged to genera of Bacillus, Pseudomonas, Acinetobacter and Arthrobacter. The result of this study indicated that the proportion of PGPRs in rhizosphere of Sophora alopecuroides is high.