Kachru R. Gawai

Decolorization and degradation of Disperse Blue 79 and Acid Orange 10, by Bacillus fusiformis KMK5 isolated from the textile dye contaminated soil

The release of azo dyes into the environment is a concern due to coloration of natural waters and due to the toxicity, mutagenicity and carcinogenicity of the dyes and their biotransformation products. The dye degrading bacterial strain KMK 5 was isolated from the textile dyes contaminated soil of Ichalkaranji, Maharashtra, India. It was identified as Bacillus fusiformis based on the biochemical and morphological characterization as well as 16S rDNA sequencing. KMK 5 could tolerate and degrade azo dyes, Disperse Blue 79 (DB79) and Acid Orange 10 (AO10) under anoxic conditions. Complete mineralization of DB79 and AO10 at the concentration of 1.5g/l was observed within 48h. This degradation potential increased the applicability of this microorganism for the dye removal.

Mechanistic investigation of decolorization and degradation of Reactive Red 120 by Bacillus lentus BI377

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.

Enzyme based cleavage strategy of Bacillus lentus BI377 in response to metabolism of azoic recalcitrant.

Bacillus lentus BI377 (B. lentus BI377) an alkaliphilic strain has accomplished the discriminate color removal strategy for Reactive Red sulfonated azoic recalcitrant irrespective of their molecular structure. During the decolorization experiment, it was observed that the diazo dye first followed chromophoric cleavage by azoreductase via typical azoreduction whereas, in case of monoazo dye, cleavage took place by peroxidase via successive electron transfers to oxide surface resulting in the asymmetric cleavage of the azo bond. Dismutation of oxidative stress by reactive metabolites has confirmed by superoxide dismutase activity. Carbon monoxide (CO) binding spectra, the content of cytochrome P450 and spectroscopy analysis by GCMS, FTIR and (1)H NMR of intermediate metabolites indicated the differentiate pattern of diazo and monoazo dye decolorization fuse to central metabolic pathway. Declined percentage of TOC and the cytotoxicity (MTT) study confirmed that environmentally benign intermediates may lead to mineralization.

Analysis of AGE modified proteins and RAGE expression in HER2/neu negative invasive ductal carcinoma.

Cancer is associated with increased glycolysis and carbonyl stress. In view of this, AGE modified proteins were identified from clinical breast cancer tissue using 2DE-immunoblot and mass-spectrometry. These proteins were identified to be serotransferrin, fibrinogen gamma chain, glycerol-3-phosphate dehydrogenase, lactate dehydrogenase, annexin II, prohibitin and peroxiredoxin 6, which have established role in cancer. Further, RAGE expression and its downstream signaling proteins NADPH oxidase and NF-kB were studied. Role of these AGE modified proteins and RAGE signaling in breast cancer is discussed.

Proteomic profiling and interactome analysis of ER-positive/HER2/neu negative invasive ductal carcinoma of the breast: towards proteomics biomarkers.

Breast cancer, especially ER positive/HER2/neu negative IDC, is the predominant subtype of invasive ductal carcinoma. Although proteomic approaches have been used towards biomarker discovery in clinical breast cancer, ER positive/HER2/neu negative IDC is the least studied subtype. To discover biomarkers, as well as to understand the molecular events associated with disease progression of estrogen receptor positive/HER2/neu negative subtype of invasive ductal carcinoma, differential protein expression profiling was performed by using LC-MS(E) (MS at elevated energy). A total of 118 proteins were identified, of which 26 were differentially expressed. These identified proteins were functionally classified and their interactions and coexpression were analyzed by using bioinformatic tools PANTHER (Protein Analysis THrough Evolutionary Relationships) and STRING (Search Tool for the Retrieval of Interacting Genes). These proteins were found to be upregulated and were involved in cytoskeletal organization, calcium binding, and stress response. Interactions of annexin A5, actin, S100 A10, glyceraldehyde 3 phosphate dehydrogenase, superoxide dismutase 1, apolipoprotein, fibrinogen, and heat shock proteins were prominent. Differential expression of these proteins was validated by two-dimensional gel electrophoresis and Western blot analysis. The cluster of these proteins may serve as a signature profile for estrogen receptor positive/ HER2/neu negative subtype.

Purification and characterization of nitroreductase from red alkaliphilic bacterium Aquiflexum sp. DL6

Nitroaromatic compounds are toxic to living organisms. Most of them exhibit human mutagenic and carcinogenic potential. Biotransformation and bioremediation processes can convert these compounds into non-toxic compounds. Acclimatization of bacterial strain Aquiflexum sp. DL6 with nitro-aromatics resulted in significant induction of nitroreductase (EC 1.5.1.34). The enzyme was purified by the combination of DEAE-cellulose and Sephadex G-100 column chromatography with 80-fold purification and 22% yield. Molecular weight of purified nitroreductase was estimated to be 29 kDa by SDS-PAGE. The enzyme characteristics were explored by varying the pH and temperatures, and the optimum activity was found at pH 9.5 and 40°C. It was revealed that the substrate specificity of nitroreductase of Aquiflexum sp. DL6 was wide for the most of the tested nitro-aromatic compounds. The kinetic parameters like Michaelis constant and velocity maxima were determined with o-nitrophenol and NADH as substrates.

Biotransformation of Nitro Aromatic Compounds by Flavin-Free NADHAzoreductase

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.

Synergistic action of flavin containing NADH dependant azoreductase and cytochrome P450 monooxygenase in azoaromatic mineralization

An alkaliphilic strain Bacillus lentus BI377 was isolated from contaminated soil of the textile area of Solapur, India. The strain was able to degrade almost 98% of recalcitrant azoic compounds by a mutually regulated process of azoreductase and a monooxygenase system. An enzyme activity study and a periodical carbon monoxide (CO) binding spectra study on a UV-visible spectrophotometer revealed that the intermediate amines formed by typical azoreduction (NN cleavage), subsequently underwent hydroxylation by the cytochrome P450 monooxygenase (CYP450) system. Azoreductase was purified by chromatographic techniques and characterization by MALDI-TOF substantiated its identity as FMN containing NADH dependent azoreductase of 32 kDa in size. Surprisingly, purified azoreductase showed the highest activity at 80 °C and pH 8.0. An increase in the activity of superoxide dismutase after decolorization confirmed the signature of oxidative stress and its involvement in the dismutation of reactive metabolites. Intermediate metabolite analysis by HPLC, GC-MS and FTIR and the removal of total organic carbon (TOC) suggested the azoaromatics’ degradation leads to mineralization via a TCA cycle.

Azoreductase: a key player of xenobiotic metabolism

Azoreductases are diverse flavoenzymes widely present among microorganisms and higher eukaryotes. They are mainly involved in the biotransformation and detoxification of azo dyes, nitro-aromatic, and azoic drugs. Reduction of azo bond and reductive activation of pro-drugs at initial level is a crucial stage in degradation and detoxification mechanisms. Using azoreductase-based microbial enzyme systems that are biologically accepted and ecofriendly demonstrated complete degradation of azo dyes. Azoreductases are flavin-containing or flavin-free group of enzymes, utilizing the nicotinamide adenine dinucleotide or nicotinamide adenine dinucleotide phosphate as a reducing equivalent. Azoreductases from anaerobic microorganisms are highly oxygen sensitive, while azoreductases from aerobic microorganisms are usually oxygen insensitive. They have variable pH, temperature stability, and wide substrate specificity. Azo dyes, nitro-aromatic compounds, and quinones are the known substrates of azoreductase. The present review gives an overview of recent developments in the known azoreductase enzymes from different microorganisms, its novel classification scheme, significant characteristics, and their plausible degradation mechanisms.

Isolation of Cytochrome P-450cam from Alkaliphilic bacteriaKocuria sp. DL

Cytochrome P-450 is a terminal oxidase, involved in biotransformation of endogenous and exogenous substances. Cytochrome P-450cam is isozyme present in various bacteria. CYP-450cam was purified from alkaliphilic bacteria, Kocuria sp. DL, isolated from pristine alkaline Crater Lake, Lonar, (Maharashtra State), India. Identification of this bacterial strain was carried out by analysis of 16S rRNA gene sequence (Kocuria species DL strain). The content of CYP-450cam was found to be 2.68 n mol/mg of protein in 50 h grown culture under aerobic condition. Purification of CYP-450cam was carried out by applying analytical procedures at 4 oC. The Km values for both aminopyrine and acetanilide were 0.4 and 0.25 mM, respectively. The maximal velocity Vmax was 12.98 and 13.2 mM/mg of protein per min for aminopyrine and acetanilide, respectively. The optimal pH and temperatures were found to be 7.4 and 40 oC, respectively. The purification fold was found to be 6. The molecular mass was found to be 48 kDa. Thermal stability of purified CYP-450cam is up to 40 oC. This enzyme has shown the characteristic type-I and type-II substrate binding spectra.