Journal of Pure and Applied MicrobiologyVol. 8 No. 2

Indole-3-acetic Acid Production by Streptomyces sp Isolated from Rhizospheric Soils of Medicinal Plants

Madhurama Gangwar*, Nagma Sharma and Preeti Saini

Department of Microbiology, Punjab Agricultural University, Ludhiana, India.

Received on 06 October 2013 and accepted on 28 December 2013



A total of 50 Streptomyces sp. isolates were obtained from rhizospheric soil of six medicinal plants. All the isolates were screened for their potential to produce IAA and 32 (64 %) isolates were able to utilize tryptophan and produce the IAA in the range of 11.40?0.1-90.33?0.50 ?g/ml. Highest amount of IAA was produced by Streptomyces Os-10 recovered from rhizospheric soils of Ocimum sanctum and Streptomyces CR-2, an isolate of Cathranthus roseus was producing minimum amount of IAA. Sequencing of 16S rDNA genes of the Streptomyces sp.Os-10 isolate had 16SrDNA gene with 99% nucleotides identity to that Streptomyces sp. VITTKGB available in Genbank database. The IAA production was maximum (110.3?1.5 ?g/ml) when the strain Os-10 was cultivated in a yeast malt extract broth amended with 2 mg/ml of L-tryptophan at pH 7.0, and incubated at 30?C with shaking at 125 rpm for 3 d. The culture filtrate from the strain Os-10 was found to stimulate significantly the root elongation of chickpea and tomato. These results suggest that IAA-producing Streptomyces Os-10 could be a promising candidate for utilization in growth improvement of plants of economic and agricultural value.

Keywords : Actinomycetes, indole-3- acetic acid, medicinal plants, Rhizosphere, Streptomyces Os-10