ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Anjaiah Gunja1, Premsagar Korripally2, Vishnuvardhan Reddy Sultanpuram3 and Thirumala Mothe1
1Microbial Ecology Laboratory, Department of Biochemistry, University College of Science,
Mahatma Gandhi University, Anneparthy, Yellareddygudem (PO), Nalgonda, Telangana, India.
2Department of Biotechnology, University College of Science, Mahatma Gandhi University,
Anneparthy, Yellareddygudem (PO), Nalgonda, Telangana, India.
3Microbztech Labs Pvt. Limited, Sri Sai Dwarakapuri Colony, Cherlapally, Nalgonda, Telangana, India.
Article Number: 11296 | © The Author(s). 2026
J Pure Appl Microbiol. 2026;20(3):2125-2135. https://doi.org/10.22207/JPAM.20.3.04
Received: 06 January 2026 | Accepted: 22 June 2026 | Published online: 16 July 2026
Issue online: September 2026
Abstract

Salt-tolerant plant growth-promoting (PGP) actinobacteria play an important role in enhancing plant tolerance to salinity stress and improving crop productivity. Here, 9 morphologically distinct actinobacterial isolates (A-I) were isolated from the rhizosphere soil of Oryza sativa cultivated in the Nalgonda district, Telangana, screened for PGP characteristics (nitrogen fixation, indole-3-acetic acid production (IAA), and phosphate solubilisation) and salt tolerance. Among them, isolate H exhibited superior PGP activity and salt tolerance, growing in media containing up to 10% NaCl. Hence, it was selected for further work. Isolate H produced cellulase, lipase, amylase and showed a positive catalase reaction. It utilised glucose, fructose, galactose, and sucrose, but not maltose. Antibiotic susceptibility analysis indicated that isolate H was partially resistant to penicillin but sensitive to tetracycline, ciprofloxacin, and vancomycin. Molecular identification based on 16S rDNA sequencing (1,356 bp) revealed that isolate H shared 99.78% sequence similarity and 99% query coverage with Streptomyces levis NBRC 15423(T), suggesting that the isolate belongs to the genus Streptomyces. Seed germination efficiency (%) revealed that the 24 hrs culture (T1) of isolate H had a significantly greater effect on rice seed germination than the 48 hrs culture (T2). The germination rate of rice seeds in T1 was 86.67%, followed by T2 (72.00%), the control (62.33%), and distilled water (55.67%), indicating that the 24 hrs grown culture of isolate H may be used to enhance rice seed germination under salt stress. This study provides preliminary evidence of the potential of a Streptomyces levis strain as a PGP bacterium under saline conditions.

Keywords

Actinobacteria, Plant Growth-Promoting Characteristics, Salt-Tolerant Strain, Antibiotic Susceptibility Analysis, 16S rDNA Sequencing

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© The Author(s) 2026. 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.