ISSN: 0973-7510

E-ISSN: 2581-690X

Madhurama Gangwar , Nagma Sharma and Preeti Saini
1Department of Microbiology, Punjab Agricultural University, Ludhiana, India.
J Pure Appl Microbiol. 2014;8(2):965-971
© The Author(s). 2014
Received: 06/10/2013 | Accepted: 28/12/2013 | Published: 31/04/2014
Abstract

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 µg/ml. Highest amount of IAA was produced  by Streptomyces TL-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.TL-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 µg/ml) when the strain TL-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 TL-10 was found to stimulate significantly the root elongation of chickpea and tomato. These results suggest that IAA-producing Streptomyces TL-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 TL-10

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