Development of a plant microbiome bioremediation system for crude oil contamination

Bacterial-assisted phytoremediation is recently being considered to be an efficient technique for remediation of crude oil-contaminated soil. The present research was designed to establish a plant microbiome bioremediation system for treating crude oil contamination. 10 strains of plant growth-promoting rhizobacteria (PGPR) were isolated from oil-contaminated soil near Oil Refinery Rawalpindi, Pakistan. Based on plant growth-promoting characteristics and biosurfactant production, two strains (Pseudoarthrobacter phenanthrenivorans (MS2) and Azospirillum oryzae (MS6)) were selected. They showed a better emulsification index (54.2, 42.5%), oil displacement activity (3.4, 2.6 mm), and hydrophobicity content (78, 75%,). For the establishment of the plant microbiome system, both strains and their combination were inoculated in rhizospheric soil of maize in crude oilcontaminated soil. Better germination attributes of maize were observed by a combination of both strains with improved fresh (32%) and dry biomass (26.5%) as compared to control under oil stress (10%). Plant microbiome bioremediation system improved the chlorophyll content (30.4%), water potential (23.2%), proline (32%), amino acids (11.1%), and antioxidant enzymes (catalase (21%), peroxidase dismutase (30%) and superoxide dismutase (22%), as compared to control under oil stress (10%). The hydrocarbons degradation efficiency of this system was 38.5%. Analysis of degradation products by GC-MS revealed the presence of low molecular weight hydrocarbons in the treated soil as compared to untreated soil. This study showed promising results by this plant microbiome system can be a way forward in bacterial assisted phytoremediation approaches at the field level in the future.

Automated summary

The study successfully improved the growth conditions of maize in crude oil-contaminated soil by establishing a plant microbiome system, increasing biomass and antioxidant enzyme activity, and effectively degrading hydrocarbon compounds. The promising results of this plant microbiome system suggest a way forward in bacterial-assisted phytoremediation approaches at the field level in the future.