Role of rhizosphere microorganisms in remediation of crude oil contaminated soil- A Review

Crude oil contamination of soil is becoming a major problem across the globe. Soil contaminated with crude oil leads to deleterious effects on soil microorganisms and plant and human health. For the purpose of remediation of oil contaminated soil, bioremediation has emerged as the most effective technique. The process by which soil pollutants are broken down by an association of plant roots and rhizosphere-dwelling microbes is called rhizoremediation. Plant roots secrete a variety of organic compounds which offer a nutrient and carbon-rich environment surrounding them enhancing the activity of rhizosphere microorganisms. The degradation of petroleum contaminants is caused primarily by the catalysis of intracellular enzymes. Depending on the components present in crude oil, the degradation mechanism is different. Different kinds of microorganisms produce different kinds of enzymes encoded by specific genes which take part in the degradation mechanisms. Being environment-friendly and cost-effective, rhizoremediation has certain limitations - it is a sluggish process and requires more time. To overcome it, there are a variety of amendments like biostimulation and bioaugmentation which increase the efficiency of the process.