Development of a plant microbiome bioremediation system for crude oil contamination

Abstract

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 oil-contaminated 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.