The synergistic effect of oil-degrading bacteria Bacillus megaterium and Bacillus subtilis on phytoremediation of oil-contaminated soils by Agropyron cristatum and Achillea millefolium, Case study: Soils around Ray refinery in Tehran

Document Type : Research Paper

Authors

1 PhD of Rangelands Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran

2 Professor of Rangeland Sciences Department, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran

3 Associate Professor, Department of Soil Sciences, Faculty of Soil and Water Engineering, Gorgan, University of Agricultural Sciences and Natural Resources, Gorgan, Iran

10.22069/ijerr.2025.21937.1417

Abstract

The objective of the present research is to assess the application of petroleum-degrading bacteria and the phytoremediation of petroleum-contaminated soils in a greenhouse experiment. For this purpose, rangeland species Agropyron cristatum and Achillea millefolium in treatments with and without inoculation with petroleum-degrading bacteria Bacillus megaterium and Bacillus subtilis for petroleum contaminated soil surrounding Tehran refinery with pollution 5.3 and 7 wt% were used. Another objective of this research is to monitor the TPH changes in the greenhouse condition with and without inoculation of bacteria for Agropyron cristatum and Achillea millefolium. The results indicated the best TPHs removal efficiency for Agropyron cristatum at the end of the growth period in the presence of Bacillus megaterium and Bacillus subtilis treatment which in 5.3 wt% contamination level, it was 72.18 and 64.08% respectively and as for Achillea millefolium it was 60.59 and 58.12% respectively. Also, the percentage of EC reduction in Agropyron cristatum at the end of the growth period in the presence of Bacillus megaterium and Bacillus subtilis treatment at 5.3 wt% contamination level was 42.37% and 39.27% respectively and as for Achillea millefolium it was 33.41 and 31.48% respectively. In the presence of bacteria, the highest pH reductions were recorded in Bacillus subtilis treatment for Agropyron cristatum with about 7.25%. Finally, it can be noted that Agropyron cristatum and Achillea millefolium cultivated in TPH-contaminated soil are resistant to oil contamination and reduce some oil contamination, however, Agropyron cristatum was superior in removing petroleum contaminants.

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Environmental Resources Research
Volume 13, Issue 2
October 2025
Pages 323-342

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