Bio-removal of Nitroaromatic Compounds
Nitroaromatic compounds are widely used in the production of explosives, pesticides, plastics, dyes, pharmaceuticals, and petroleum products and are mutagenic, carcinogenic and highly stable and therefore pose an ever present and dangerious contaminant in the environment (Ye et al., 2004). Because many bacteria able to process these compounds are very specific, current research in the bioremediation of nitroaromatics is looking towards combining metabolic pathways in bacteria to degrade a wide range of these pollutants (Kulkarni et al., 2007). As of the current state, limited knowledge of degradation pathways inhibit this approach. Our approach is slightly different in that rather than biodegrading these compounds through combining existing pathways, we will attempt to have bacteria store these compounds within its membrane and then remove the bacteria from the contaminated site.
Because bacteria such as E. coli and other bacteria have been engineered to process these compounds (Kadiyala et al., 2003) we assume that these bacteria already have a method of transporting these compounds within the cytoplasm. Furthermore, E. coli produces nitroreductase, an enzyme, present in many strains of bacteria, reduces the nitro group and is active in numerous metabolic pathways. In our project, we will attempt to engineer this enzyme so that it will bind irreversibly to the nitro groups of common nitroaromatic pollutants such as TNT and RDX. We will attempt to model this bond after the bond between carbon monoxide and hemoglobin.
After binding, the nitroaromatic compounds are then stored within the membrane of these bacteria. The bacteria may be removed by methods that include magnetic taxis. The removal of bacteria will be the subject of subsequent research.
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