Biotransformation of Nitro Aromatic Compounds by Flavin-Free NADHAzoreductase

Abstract

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.

Human Gut Microbiota and Drug Metabolism

“…The bacterial genera Clostridium sp., Eubacterium sp., Clostridium leptum , C. paraputrificum , C. perfringens , and C. clostridiiforme exhibited nitroreductase and azoreductase activities in the human GI tract [ 101 – 104 ]. Misal and Gawai have classified azoreductase superfamily into five different groups, depending upon their preference for nicotinamide and flavin: (1) flavin-containing NADPH-dependent azoreductase [ 105 , 106 ], (2) flavin-containing NAD(P)H-dependent azoreductase [ 107 – 110 ], (3) flavin-containing NADH-dependent azoreductase [ 111 , 112 ], (4) flavin-containing NAD(P)H-dependent quinine oxidoreductases [ 113 , 114 ], and (5) flavin-free NAD(P)H-dependent azoreductase [ 115 – 118 ]. Azo drugs like olsalazine, asacol, pentasa, balsalazide, azulfi dine, and salazopyrin for the treatment of ulcerative colitis and inflammatory bowel disease (IBD) [ 119 , 120 ] are pro‐drugs, having 5‐aminosalicylate (5‐ASA), a non-steroidal anti-inflammatory molecule, and an inert carrier are linked with an azo bond, in order to avoid their rapid adsorption [ 121 , 122 ].…”

Electron transport phenomena of electroactive bacteria in microbial fuel cells: a review of Proteus hauseri

“…That is, they were susceptible to reduction, and not easy to be oxidatively catabolized in aerobic environments (Ju and Parales 2010;Knackmuss 1996;Kulkarni and Chaudhari 2007). These similar reductive characteristics all supported that nitroreductases and azoreductases may originally derive from similar enzymatic systems (Hsueh et al , 2017Misal et al 2015;Cerniglia 1993, 1995;Rau and Stolz 2003).…”

Comparative Genomic Analysis of Antarctic Pseudomonas Isolates with 2,4,6-Trinitrotoluene Transformation Capabilities Reveals Their Unique Features for Xenobiotics Degradation

“…In addition to the already mentioned TNT-degrading enzymes, azoreductases (AzoRs) can also participate in TNT degradation. Generally, AzoRs catalyze the cleavage of azo bonds (–N=N–) of aromatic azo dyes, but some of them have been reported to also have nitroreductase activity, including TNT reduction [ 104 , 105 , 106 ]. In addition, it has been demonstrated that the gene encoding AzoR1 in P. putida KT2440 is upregulated when this bacterium is grown in the presence of TNT [ 30 ].…”