Biotransformation of Nitro Aromatic Compounds by Flavin-Free NADH-Azoreductase

Nitro aromatic compounds are the potential toxic organic pollutant released into the environment and are often resistant to degradation under normal environmental conditions. The biotransformation and/or detoxification of these compounds can be possible by microbial azoreductase enzyme. Azoreductase enzyme has an ability to reduce the toxic nitro group to corresponding amino group. In present report, the flavin-free NADH azoreductase was isolated and purified from alkaliphilic bacteria Bacillus badius. The enzyme was purified by a combination of ammonium sulphate precipitation and size exclusion chromatography. The purified azoreductase has efficiently demonstrated both azoreductase and nitroreductase activities. The biochemical properties of the azoreductase including cofactor requirement, substrate specificity and enzyme inhibition have been studied. The biotransformation of some selected nitro aromatic compounds like 3-nitro benzoic acid, 4-nitro toluene, 3-nitro toluene and 1-chloro-2-nitro benzene by purified azoreductase was carried out at 37°C. The reduction products of these nitro aromatic compounds were analyzed by IR and NMR spectroscopy. Citation: Misal SA, Humne VT, Lokhande PD, Gawai KR (2015) Biotransformation of Nitro Aromatic Compounds by Flavin-Free NADH-Azoreductase. J Bioremed Biodeg 6: 272. doi:10.4172/2155-6199.1000272 Volume 6 • Issue 2 • 1000272 J Bioremed Biodeg ISSN: 2155-6199 JBRBD, an open access journal Page 2 of 6 [17]. The azoreductases from alkaliphilic microorganism were not studied in this point of view so far. However, different forms of azoreductase and nitroreductases are also isolated from several aerobic and anaerobic bacteria [18-20]. Numerous azoreductases have been characterized from variety of fungal and bacterial strains, but alkaliphilic azoreductases are still not well explored. In our previous efforts, we isolated various alkaliphilic bacterial strains from alkaline Crater Lake of Lonar and studied different types of azoreductases and nitroreductases [13,14,21]. Since these enzymes are the key enzymes in biotransformation and biodegradation processes of xenobiotic, very little data is available on azoreductases which have the highly stable properties such as temperature and pH. Thus, the present report demonstrates the properties of flavinfree NADH-azoreductase from alkaliphilic bacteria B. badius and its ability to transform some selected nitro aromatic compounds to its corresponding amines. Materials and Methods