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Development of a bacterial consortium comprising oil-degraders and diazotrophic bacteria for elimination of exogenous nitrogen requirement in bioremediation of diesel-contaminated soil

Chaudhary, Dhiraj Kumar, Bajagain, Rishikesh, Jeong, Seung-Woo, Kim, Jaisoo
World journal of microbiology & biotechnology 2019 v.35 no.7 pp. 99
Acinetobacter, Azotobacter vinelandii, ammonium nitrate, bioremediation, nitrogen, nitrogen fixation, nitrogen-fixing bacteria, polluted soils, total nitrogen
The purpose of this study was to develop an effective bacterial consortium and determine their ability to overcome nitrogen limitation for the enhanced remediation of diesel-contaminated soils. Towards this, various bacterial consortia were constructed using oil-degrading and nitrogen-fixing microbes. The diesel removal efficiency of various developed consortia was evaluated by delivering the bacterial consortia to the diesel-contaminated soils. The consortium Acinetobacter sp. K-6 + Rhodococcus sp. Y2-2 + NH₄NO₃ resulted in the highest removal (85.3%) of diesel from the contaminated soil. The consortium containing two different oil-degrading microbes (K-6 + Y2-2) and one nitrogen-fixing microbe Azotobacter vinelandii KCTC 2426 removed 83.1% of the diesel from the soil after 40 days of treatment. The total nitrogen content analysis revealed higher amounts of nitrogen in soil treated with the nitrogen-fixing microbe when compared with that of the soil supplemented with exogenous inorganic nitrogen. The findings in this present study reveal that the consortium containing the nitrogen-fixing microbe degraded similar amounts of diesel to that degraded by the consortium supplemented with exogenous inorganic nitrogen. This suggests that the developed consortium K-6 + Y2-2 + KCTC 2426 compensated for the nitrogen limitation and eliminated the need for exogenous nitrogen in bioremediation of diesel-contaminated soils.