Xenobiotics are synthetic man-made compounds; their increased use affects the human health and cause severe diseases.  It also covers chemical substances that are released in high concentration in environment. Different xenobiotics i.e DDT (dichlorodiphenyltrichloroethane), pyrethroids, some other chlorinated compounds has critical severe impact on environment. Such types of chemicals cannot be easily removed from the environment through living organism’s metabolism. Living organisms mainly bacteria, fungi produced extracellular enzymes that attack on the chemical structure of the xenobiotics. Through microbial metabolism xenobiotics degraded from toxic to non-toxic compounds which are mainly environmental accepted form. Enzymes play important role in xenobiotics degradation are Laccases, dehydrogenases, oxidoreductases etc. Degradation of xenobiotics  through microbial system is a cost effective way to reduce such type of problem. Bacterial species like Pseudomonas, Flavobacterium, Sphingobium, Arthrobacter, Xanthobacter etc. have been isolated from soil and characterized for their degradation potential.

Table.1: List of some potential microorganisms degraded the toxic xenobiotics from the environment

Microbial consortium

Microbial consortium is the combination of bacterial and fungal strains. In combination microbes have the great efficiency to complete removal of the toxic xenobiotic compounds. Different species of the bacteria and fungi can be used for the formation of microbial consortium from indigenous bacterial strains. Previously several researchers reported the microbial consortium that is available commercially for the removal of toxic pollutants from environment.

Metabolic engineering for biodegradation of Xenobiotics

The word metabolome was first used less than a decade ago to refer to all low molecular mass compounds produced and modified by living organisms. Many organisms naturally degrade xenobiotics, only there are some organisms that degrade several different xenobiotics. In bioremediation it is attractive to have a few organisms that can degrade several different compounds. This may be achieved either by inserting pathways from other organisms or through engineering of the existing pathways. With the development of genetic engineering tools it is very easy to modify the microbial pathways for biodegradation of the xenobiotics. We can collect the beneficial genes from different organisms and use this combination for the degradation of many pollutants/ xenobiotics at a time. Such artificial gene expression is possible with the help of different cloning vectors i.e  popularly known as plasmids.

Microbial based biodegradation of the xenobiotics is safe and alternative method to physico-chemical methods. The potential microbes have been isolated that are capable of mineralizing variety of persistent and toxic compounds from the nature. Day by day new compounds are synthesizes by chemical industries that cannot be degraded through the natural microbial mechanisms. Because for new compounds microorganisms do not have degradative pathways against each compounds.Besides these factors, the organism capable of degradation must be present at the site where it is needed and it has to perform under the given or manipulated environmental conditions. Thus, a combined approach is required to understand the bottlenecks of xenobiotic degradation, to rationally overcome them by different (genetic) engineering methods, to elucidate the microbial metabolic diversity and to understand the metabolic and organismic network necessary for activity under environmental conditions.

Conclusion and future aspect

The quality of life on earth is linked inextricably to the overall quality of environment. By knowing the scientific facts we can reduce the use of toxic pollutants from our daily needs. Now a day’s many of the daily consumable items in our surrounding contain lot of xenobiotics. At large scale we can control the level of such hazardous pollutants from environment using microbial system which is available in nature everywhere. More advancement for development of genetic engineering tools we can develop the unique microbial system for the complete removal of xenobiotics from environment.