Investigation of Effects of Ecological Factors on the Establishment of Azotobacter in the Rhizosphere of Thyme (Thymus vulgaris)

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Nathaniel N. Ngerebara
Lawrence O. Amadi


Aim: The present study investigates the effect of phosphate-solubilizing bacteria (phosphobacteria (PB) and activity of soil bacteriostasis on the development of Azotobacter in Thymus vulgaris rhizosphere.

Place and Duration of Study: The study was conducted at Kenule Beeson Polytechnic botanical garden and at the Science Laboratory Department of the institution for a period of 7months (from March 2018- September 2018). 

Methods: The impact of phytohormones produced by phosphate-solubilizing bacteria in vitro and in the rhizosphere of T. vulgaris was used to assay for Azotobacter colonization. Bacteriostasis activity of the soil was determined by comparing the number of Azotobacter microcolonies on discs incubated over soil with respect to those on the controls.

Results: Decisive stimulation of Azotobacter population and establishment was observed in Thymus vulgaris rhizosphere when inoculated with phosphobacteria than when inoculated alone as reflected in 5% (0.05) least significant difference. Azotobacter was susceptible to the bacteriostatic factors in potted soils inoculated with it and without (Azotobacter). The increase in susceptibility of this rhizospheric bacteria was time dependent and reached a maximum and thereafter remained almost constant. However, this was overcome by the addition of NPK fertilizer to the plant at some critical stage of the assay.

Conclusion: The Presence of nitrogen fixing bacteria (NFB) in vegetation could play significant role in the sustainability and improvement of plant growth and yield. Soil bacteriostasis can also be an important factor that limits the survival and development of NFB.

Thymus vulgaris, sensitivity, bacteriostasis, phosphobacteria, Azotobacter.

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How to Cite
Ngerebara, N. N., & Amadi, L. O. (2020). Investigation of Effects of Ecological Factors on the Establishment of Azotobacter in the Rhizosphere of Thyme (Thymus vulgaris). South Asian Journal of Research in Microbiology, 8(1), 22-27.
Original Research Article


Ngerebara NN, Ogan AC. Effects of soil bacteriostasis and phosphobacteriaon the establishment of Azotobacter in the rhizosphere. J Science and Technol Research Centre for Development of Strategies. 2015;9(1):1-7.

Ngerebara NN, Ogan AC. Selected colonization of the rhizosphere of wheat by nitrogen-fixing bacteria. J. Gen. Microbiol. 2013;42:125-144.

Suryatmana P, Anggraini DA, Kamaluddin NN, Setiawati MR. Nitrogen-fixing Bacteria inoculation (NFB) and Compost Application in Phytoremediation of Petroleum-Contaminated Soils using Ramie plant (Boehmeria nivea L). Int’l J Agric., Environ, Bioresearch. 2020;5(04):8-18.

Gałązka A, Król M, dan Perzyński A, The efficiency of rhizosphere bioremediation with Azospirillum sp. And Pseudomonas stutzeriNisoils freshly contaminated with PAHs and diesel fuel. “Pol J. Environ Study. 2012;21(2):345-353.

Murcia RB, Rodelas V, Salmertn MV, Martlnez-Toledo dan J, Gonzalez-Lopez. Effect of the herbicide simazine on vitamin production by Azotobacter chroococcum and Azotobacter vinelandii. Applied Soil Ecology.1997;6(2):187-193.

Dommergues YJ, Mangenot FT. (2001). Ecologie Microbienne du sul. Paris. Masson et C. 2001;796.

Mishustin AN, Shilnikova VK. Biological fixation of atmospheric nitrogen. Nature. 2000;171:189-191.

Brown MA. Soil bacteriostatic limitation in growth of soil and rhizosphere bacteria. Can. J. Microbial. 2002;18:182-190.

Ocampo JC, Brown JV, Minonye EC. Interactions between Azotobacter and phosphobacteria and their establishment in the rhiozsphere as affected by soil fertility. Can J. Microbial. 2005;20:1150-1160.

Stotzky FG. Activity, ecology and population dynamics of microorganisms in soil. Critical Rev. Microbial. 2003;2:52-120.

Brown EM. Seed and root bacterization. Ann. Rev. Phytopathol. 2001;12:180-190.

Jackson JJ, Brown EM. Behavior of Azotobacter chroococcum introduced into the plants rhizosphere. Ann. Inst. Pasteur. 2003;110:105-112.

Barea JV, Nelson EJ, Palomares AJ, Esther ME. A rapid microbiological assay method for auxins, gibberellic acid and kinetin using yeast. J. Appl. Bacteriol. 2004;37:560-580.

LU KC, Gilbert CN, Zigallo AB, Boyle OK. Effects of gibberellic acid on the growth and multiplication of some soil microorganisms and unicellular green algae. Nature. 2011;204:1228-1230.

Saono SZ. Effect of gibberellic acid on the growth and multiplication of some soil microorganisms and unicellular green algae. Nature. 2001;205:1220-1229.

Sullia MB. Effect of foliar spray of hormones on the rhizosphere microflora of leguminous seed. Plant and Soil.2005;27:290-295.

Suryatmana P, Fauzi M, Setiawati MR, Bety NF. The biofertilzer’s effect on phytoremediation performance by using Boehmeria nivea L. Gaud on petroleum hydrocarbon contaminated soil. Academic Journal of Science. 2018;8(1):31–42.

Patti PS, Kaya E, danSilahooy Ch. Analisisstasiun nitrogen tanahdalam Kaitannya dengan serapan N oleh tanaman padi sawah di Desa Waimital, Kecamatan Kairatu, Kabupaten Seram bagian barat. Jurnal Agrologia. 203;2(1):51-58.