Bacterial communities and their bioremediation capabilities in oil-contaminated agricultural soils

Rapid industrialization and development in petrochemical industries have resulted in increased hydrocarbon pollution causing substantial damage to the natural ecosystems including agricultural soils. In the recent, past efforts have been made to treat the contaminated soils using microorganisms by natural processes. Soil bacteria, known for their potential to degrade the soil contaminants, play a vital role in maintaining soil health. In the current study, we observed the influence of hydrocarbon contamination on the physicochemical characteristics and enzymatic activities of the soil. Proteobacteria (30.48%), Actinobacteria (13.91%), and Acidobacteria (12.57%) flourished in the non-contaminated soil whereas contaminated sites were dominated by Proteobacteria (44.02 +/- 15.65%). In contrast, the sites experiencing the different degrees of exposure to the hydrocarbon pollution allowed specific augmentation of bacterial taxa (in decreasing order of exposure time), viz. Proteobacteria (60.47%), Firmicutes (32.48%), and Bacteroidetes(13.59%), based on culture-independent approach that suggested their potential role in hydrocarbon degradation as compared to the non-contaminated site. The imputation of metabolic function also supported the positive correlation to the exposure to hydrocarbon pollution, with site 2 being highly abundant for gene families involved in xenobiotics biodegradation. The study provides insights into bacterial community structure with special emphasis on their efficiency to degrade hydrocarbons. The results from the study can help in designing appropriate biodegradation strategies to mitigate the serious problems of oil contamination in agricultural soil.