ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Devendra Jain1 , Gunnjeet Kaur1,2, Ali Asger Bhojiya1,3, Surya Chauhan1,S.K. Khandelwal1, R.H. Meena4, Deepak Rajpurohit1 and Santosh Ranjan Mohanty5
1Department of Molecular Biology and Biotechnology, Rajasthan College of Agriculture,
Maharana Pratap University of Agriculture and Technology, Udaipur – 313 001, Rajasthan, India.
2School of Agricultural Sciences, Dr. K. N. Modi University, Newai, Tonk – 304 021, Rajasthan, India.
3Department of Agriculture and Veterinary Sciences, Mewar University, Chittaurgarh – 312 901, Rajasthan, India.
4Department of Soil Science and Agricultural Chemistry, Rajasthan College of Agriculture, MPUAT, Udaipur 313 001, Rajasthan, India.
5Indian Institute of Soil Science, Indian Council of Agricultural Research, Bhopal – 462 038,
Madhya Pradesh, India.
J Pure Appl Microbiol. 2021;15(1):428-436 | Article Number: 6671 | © The Author(s). 2021
Received: 29/09/2020 | Accepted: 16/12/2020 | Published: 27/02/2021

The present research was conducted to characterize the indigenous plant growth promoting (PGP) Azotobacter strains isolated from plant root interface of semi-arid regions of Rajasthan (India) and to study their potential to be used as bio-fertilizers. A total of 172 Azotobacter strains were isolated, purified and based on the morphological test i.e. gram staining, pigmentation, cyst formation, fluorescence etc, broadly classified as Azotobacter. Further the secluded strains were examined for biochemical analysis and plant growth promoting characters. All the isolates showed different biochemical characteristics and significant PGP traits. IAA activity of the Azotobacter strains ranges from 54.5-6000 µg/mL. Ammonia, HCN and siderophore was produced by 92.4%, 78.4% and 80.23% of the total isolates respectively. Solubilization of phosphate was observed in 97.6% of the total isolates. These strains were also characterized for qualitative and quantitative N2 fixation abilities and the result indicated that 114 strains showed positive results on nitrogen free malate agar medium (NFMM) containing bromothymol blue (BTB) and able to produce 18.93-475.6 N-moles C2H4 mg protein−1 h−1 of acetylene reduced by Azotobacter strains. In vitro pot studies revealed that the selected native Azotobacter strains having high ARA results significantly increase the plant growth characters. Shoot length, root length, root number and chlorophyll content and leaf number increases by 45.62%, 17.60%, 97.49%, 49.69% and 27.83% respectively in pot inoculated with AZO23-3 as compared to control. These effective strains can further be utilized for development of effective microbial formulations.


Biochemical Test, Cyst, Pigmentation, Antibiotic sensitivity, Acetylene Reductase Assay, Pot study

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© The Author(s) 2021. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.