Biotransformation of nitroaromatics and their effects on mixed function oxidase system
ABSTRACT Acinetobacter junii A8 was able to biotransform nitroaromatic compounds like o-nitroaniline, o-nitrotoluene, m-nitrotoluene, 2,4,6-trinitrotoluene and o-nitrophenol under aerobic condition, within 36 h of incubation. These compounds, which are normally considered to be toxic to microorganisms, caused the induction of drug metabolizing enzymes such as cytochrome P-450, aminopyrine N-demethylase, acetanilide hydroxylase and glutathione S-transferase. These enzymes constitute the bacterial mixed function oxidase system. Induction of this system implies its involvement in biotransformation of these nitro compounds. The biotransformed metabolites were characterized by IR, 1H NMR and GC–mass spectroscopy. It was observed that o-nitroaniline and m-nitrotoluene were reduced to their respective amines, whereas o-nitrotoluene was oxidized to acid. However, 2,4,6-trinitrotoluene (TNT) and o-nitrophenol were completely mineralized. The metabolites of TNT biotransformation were characterized as 2,6-dinitro-4-nitrosotoluene, 4-amino-2,6-dinitrotoluene and 4-amino-2,6-dinitrobenzoic acid. The result of this study showed that these nitroaromatics induced the mixed function oxidase system, which resulted in the degradation of these compounds.
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ABSTRACT: Bacillus lentus BI377, isolated from textile effluent-contaminated soil, was able to degrade 97% and 92% of Reactive Red 120 dye when 1200 and 1500 mg/l, respectively, of dye was added to nutrient broth (NB) at 35 °C within 12 h. UV-vis spectroscopy, GC-MS, FTIR and 1H NMR revealed the formation of catechol which may be further utilized by the bacterium via the TCA cycle, leading to complete mineralization. Structural analysis of metabolites in conjunction with enzyme activity studies confirmed the involvement of azoreductase, cytochrome P450 monooxygenase and other antioxidant enzymes. Decreases in total organic carbon and in biological and chemical oxygen demand suggest formation of low molecular weight metabolites that could be completely mineralized. These results suggest the potential use of B. lentus BI377 towards online treatment of textile dye effluents by using an appropriate bioreactor over a wide range of pH. This study opens-up a dependable and proficient way to use industrially viable non-pathogenic strains for biotransformation of carcinogenic dyes to ecofriendly compounds.Bioresource Technology 01/2011; 102(2):758-64. · 5.04 Impact Factor
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ABSTRACT: To evaluate the potential of Brevibacillus laterosporus MTCC 2298 for the decolourization of different textile azo dyes including methyl red, mechanism of biotransformation and the toxicity of products. Brevibacillus laterosporus showed decolourization of thirteen different azo dyes including methyl red. Decolourization of methyl red was faster (93% within 12 h) under static condition at the concentration 0.2 g l(-1). Induction in the activities of lignin peroxidase, laccase, aminopyrine N-demethylase, NADH-DCIP reductase and malachite green reductase was observed in the cells obtained after decolourization. Fourier transform infra-red spectral analysis of products indicated conversion of methyl red into secondary aryl amines and nitrosamines, which further transformed into the aromatic nitro compounds. Gas chromatography-mass spectroscopy analysis suggested conversion of methyl red into high molecular weight complex derivatives. The heterocyclic substituted aryl amine (m/z 281), p-(N,N di formyl)-substituted para-di amino benzene derivative (m/z 355) and p-di-amino benzene derivative (m/z 282) are the mainly elected biotransformation products. Microbial and phytotoxicity studies suggested nontoxic nature of the biotransformation products. Brevibacillus laterosporus has potential for the decolourization of different textile azo dyes. Brevibacillus laterosporus decolourized different azo dyes including methyl red and can be utilized for textile dye decolourization.Journal of Applied Microbiology 02/2009; 106(3):993-1004. · 2.20 Impact Factor