ABSTRACT
Industrialization and other human activities have led to release of toxins into the environment, and our planet is becoming polluted with a wide variety of pollutants, most of which are carcinogenic. Most polluted sites often contain a mixture of both organic and inorganic pollutants (Ensley 2000). It is estimated that around $6-8 billion is spent each year on environmental cleanup in the United States (Glass 1999) and around $25-50 billion globally (Tsao 2003). The most commonly used methods for clean up are the engineering-based methods such as pump and treat, excavation, soil washing, capping and burning. These are environmentally invasive and extremely expensive. Biological methods (bioremediation), such as bioaugmentation using special microbes, are also being used to treat contaminated sites. Bioremediation can occur on its own or can be spurred on via addition of superior strains of pollutant-degrading microbes. However, there are multiple challenges to bioremediation. For example, use of additional substrates or co-metabolites makes the whole process expensive. Although microbes can utilize a wide variety of organic compounds thereby converting them to nontoxic forms, survival at a particular site, bioavailability of the pollutant, and the presence of inducers to activate expression of necessary enzymes are some factors that need to be considered before bioremediation can be used.
