Rapid phenanthrene biodegradation in highly calcareous saline sodic soil using an artificial halophile bacterial consortium

Annually, a considerable quantity of petroleum products enter the natural resources, which gives rise to a multitude of environmental issues. Salinity and the high content of sodium and calcium carbonate (CaCO₃) are three of the principal factors that restrict the refining of polycyclic aromatic hydrocarbons (PAHs) in soils. The optimal approach to overcoming this limitation is the utilisation of salt-tolerant bacteria with the ability to break down petroleum compounds. In this study, the capacity of an artificial halophile consortium comprising native salt-tolerant bacteria with the ability to degrade phenanthrene (Halobacillus sp. strain Q-SH1, Acidovorax sp. strain Q-SH3, Bacillus sp. strain Q-SH12, and Bacillus sp. strain Q-SH14) and natural consortium (isolated from phenanthrene-oil enriched soil) was investigated in the removal of phenanthrene from calcareous saline-sodic soil. The consortia were inoculated to the microcosm treatments which contained calcareous saline-sodic soil with 47% CaCO₃, an electrical conductivity (EC) of 30 dS/m (nearly 2% soil salinity) and phenanthrene at a 250 mg/kg concentration under both aeration and non-aeration conditions (28 °C, 90 days incubation). The outcomes of the respiration, dehydrogenase activity, and microbial population tests indicated that the artificial consortium + phenanthrene under aeration conditions exhibited the highest activity (P < 0.05). Furthermore, the results of gas chromatography (GC) demonstrated that this artificial halophile consortium was able to rapidly removing over 90% of phenanthrene (250 mg/kg) from highly saline-affected soil, in conjunction with a high lime content within 15 days. Consequently, this bacterial consortium is an appropriate candidate for the removal of phenanthrene from polluted calcareous saline-sodic soil.