Microbial diversity: Application of microorganisms for the biodegradation of xenobiotics

Environmental pollution caused by the release of a wide range of compounds as a consequence of industrial progress has now assumed serious proportions. Thousands of hazardous waste sites have been generated worldwide resulting from the accumulation of xenobiotics in soil and water over the years. Nitroaromatic compounds (NACs), polycyclic aromatics and other hydrocarbons (PAHs) that are constituents of crude oil, and halogenated organic compounds together constitute a large and diverse group of chemicals that are responsible for causing widespread environmental pollution. The physico-chemical remedial strategies to clean up sites contaminated by these compounds are not cost effective or adequate enough. Therefore, research is increasingly being focused on biological methods for the degradation and elimination of these pollutants. Sites contaminated by these compounds need urgent remedial solutions, the search for which has revealed a diverse range of bacteria that can utilize these xenobiotics as substrates, often mineralizing them or converting them into harmless products, and in the process helping to clean up the environment. New genes, enzymes and metabolic routes involved in bacterial degradation of PAHs, NACs and halogenated organic compounds (HOCs) have been discovered, and new methods have been developed which allow the discovery and broad flexibility of microorganisms in environmental clean up. Studies to understand the interaction between xenobiotics and microorganisms in the environment have to intersect with biochemical and genetic engineering areas. Such a strategy will provide the ground for successful interventions into environmental processes and ultimately lead to optimized strategies for tapping of microbial diversity for efficient and effective bioremediation of xenobiotics.