International Journal of Life Science and Agriculture Research

Nitrogen-fixing endophytic bacteria play an important role in improvingnitrogen availability and supplying growth-promoting factors to plants. This study evaluated the potential of endophytic bacterial isolates obtained from various plants growing under saline conditions based on their nitrogenase activity, indole-3-acetic acid (IAA) production, and ability to promote rice seedling growth. A bioassay was conductedusing rice seedlings grown in Fahraeusmedium adjusted to a salinity level of 4 dS m⁻¹. The experiment was arranged in a randomized complete block design with eight treatments consisting of an uninoculated control and seven selected endophytic bacterial isolates, with three replications. The measured responses included shoot length, root length, shoot dry weight, root dry weight, and total seedling biomass. Based on the bioassay results, two superior isolates, A1 and A2, were identified. The isolates exhibited nitrogenase activities of 1.223 and 1.780 µmol mL⁻¹ g⁻¹ h⁻¹, respectively, and produced IAA at concentrations of 7.819 and 7.794 mg L⁻¹, respectively. They increased root length by 13.66% and 15.44%, respectively, and resulted in numerically higher total seedling dry biomass, with values 51.99% and 34.68% higher than the uninoculated control, respectively. These findings indicate that the selected halotolerant nitrogen-fixing endophytic bacterial isolates can promote rice seedling growth under saline conditions and have potentialfor further development as biological fertilizers for rice cultivation on saline soils.

Nitrogen-fixing endophytic bacteria, superior isolates, bioassay.

1. Akmalia D., and Budi SW. (2026). Biofertilizers and Their Regulation in Indonesia. Asia-Pacific Biofertilier and Biopesticides Information Platform. https://apbb.fftc.org.tw/article/830
2. Baldani V.L.D., BaldaniJ.I., Olivares F., and Dobereiner J. (1992). Identification and ecology of Herbaspirillum seropedicae and the closely related Pseudomonas rubrisubalbicans. Symbiosis. 13:65-73.
3. Doty S. L., Oakley B., Xin G., Kang J. W., Singleton G., Khan Z., Vajzovic A., and Staley J. T. (2009). Diazotrophic endophytes of native black cottonwood and willow. Symbiosis, 47(1):23-33.
4. Gofar N., Widjajanti H., and Marlina N. (2015). Stimulate the growth of rice using endophytic bacteria from lowland rice plant tissue. Sains Tanah – Journal of Soil Science and Agroclimatology, 12 (2): 45-52. http://jurnal.fp.uns.ac.id/index.php/tanah/
5. Gomez K.A. Gomez A.A. (1995). Statistical Procedures for Agricultural Research. John Wiley & Sons. New York.
6. Harni R., Saefudin, Sasmita KD, Sakirohand Amaria W. (2023). Efficacy of organicfertilizer, biofertilizer and endophytic bacteria to controlnematodes in robustacoffee. IOP Conf. Series: Earth and Environmental Science IOP Publishing 1208 (2023) 012017 doi:10.1088/1755-1315/1208/1/012017
7. Iniquez A L, Dong Y and Triplett E W. (2004). Nitrogen fixationin wheat providedby Klebsiella pneumonia 342. Molecular Plant-Microbe Interactions 17(10): 10781085.
8. James K. and Olivares F.L. (1997). Infection and colonization of sugar cane and other Graminaceous plants by endophytic diazotrophs. Crit. Rev. Plant Sci. 17:77–119.
9. Leveau J. and Lindow S. (2005). Utilization of the plant hormone indole-3-acetic acid for growth by pseudomonas putida strain 1290. Applied and Environmental Microbiology. 71. 2365-71. 10.1128/AEM.71.5.2365-2371.2005.
10. Lindstrom K. and MousaviSA. (2019). Effectiveness of nitrogen fixationin rhizobia. Microbial Biotechnology, 13: 1314–1335
11. Mohidem NA., Hashim N., Shamsudin R., Che Man, H. (2022)Rice for Food Security: Revisiting Its Production, Diversity, Rice Milling Process and Nutrient Content. Agriculture, 12, 741: 1-28. https://doi.org/10.3390/agriculture12060741
12. Montes-Luz B., Conrado AC., Ellingsen JK., Monteiro RA., de Souza EM., StaceyG. (2023). CurrentProtocols. Acetylene Reduction Assay: A Measure of Nitrogenase Activity in Plants and Bacteria. Current Protocols. https://doi.org/10.1002/cpz1.766
13. Muangthong A., Youpensuk S., Rerkasem B. (2015). Isolation and characterisation of endophytic nitrogenfixing bacteria in sugarcane. Tropical Life Sciences Research, 26(1): 41–51.
14. Nuriyanah, Widowati T., Masnang A., Nurjanah L, Novilasari D., Lekatompessy SJR., Simarmata R. (2023). Screening and characterization of endophytic bacteria isolated from celery with the potential to promote plant growth. Biodiversitas 24. 12: 6898- Nagah A, El-Sheekh MM, Arief OM,
15. Pelczar MJ., JR., Chan ECS., Krieg NR. (2012).Microbiology. 5 ed. Tata McGrawHill. New Delhi.
16. Peng Y., HeY., Wu Z., Lu J., Li C. (2014). Screening and optimization of low-cost medium for Pseudomonas putida Rs-198 culture using RSM. Brazilian Journal of Microbiology 45, 4, 1229-1237.
17. Rachman A., Dariah A., dan SutonoS. (2018). Management of high salt content salinerice fields. IAARD Press. Jakarta
18. Rana KL., Kour D, Kaur T., Negi R., Devi R., Yadav N., Rai PK., Singh S., Rai AK., Yadav A., Sayyed RZ., Yadav AN. (2023). Endophytic nitrogen-fixing bacteria: Untapped treasurer for agricultural sustainability. Journal of Applied Biology & Biotechnology. 11(2): 75-93.
19. Sen A., Saji J., Faseela P, Zhang C., Mohanan S., Xia Y. (2026). Exploring the functional roles of endophytic bacteria in plant stress tolerance for sustainable agriculture: diversity, mechanisms, applications, and challenges. Plants 15, 206:1-25. https://doi.org/10.3390/plants15020206
20. Shi Y., Lou, K., and Li, C. (2009). Isolation, quantity distribution and characterization of endophytic microorganisms within sugar beet. African Journal of Biotechnology, 8(5).
21. Sukarman, MulyaniA., Purwanto S. (2018). Modification of climate change-oriented land suitability evaluation methods. Jurnal Sumberdaya Lahan, 12(1): 1-11.
22. Tarun, Kalpna, Thakur K., Mall S., Katoch M., Jahnawe S., Paul JJJ., Brohma S., Sahoo M., Kalia S., Kaur G. (2026). Endophytes and their significance in plant health and agricultural sustainability. Journal of Applied Biology & Biotechnology 2026;14(5):23-34