Decolorization and degradation of xenobiotic azo dye Reactive Yellow-84A and textile effluent by Galactomyces geotrichum.

Galactomyces geotrichum MTCC 1360 exhibited 86% decolorization of azo dye Reactive Yellow-84A (50mgL(-1)) within 30h at 30°C and pH 7.0 under static condition. Examination of azoreductase, laccase and tyrosinase enzyme activities confirmed their prominent role in Reactive Yellow-84A degradation. Considerable reduction of COD (73%) and TOC (62%) during degradation of the dye was indicative of conversion of complex dye into simple products, which were further analyzed by HPLC, FTIR, GC-MS and HPTLC. The degradation products were identified as 4(5-hydroxy, 4-amino cyclopentane) sulfobenzene and 4(5-hydroxy cyclopentane) sulfobenzene by GC-MS. In addition, when G. geotrichum was applied to decolorize textile effluent, it showed 85% of true color removal (ADMI removal) within 72h, along with a significant reduction in TOC and COD. Phytotoxicity studies revealed the less toxic nature of degraded Reactive Yellow-84A as compared to original dye.

Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria.

The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO3 solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5-50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis.

Differential catalytic action of Brevibacillus laterosporus on two dissimilar azo dyes Remazol red and Rubine GFL.

This comparative study disclosed the diverse catalytic activities of Brevibacillus laterosporus on two different azo dyes. It decolorized 100% of Remazol red and 95% of Rubine GFL within 30 and 48 h respectively, under static condition at 50 mg l⁻¹ dye concentration. Significant increase was observed in azo reductase, NADH-DCIP reductase, veratryl alcohol oxidase and tyrosinase in cells obtained after decolorization of Remazol red; whereas these values were much different with complete inhibition of azo reductase during decolorization of Rubine GFL. The plausible pathway of dye degradation obtained from Gas chromatography-Mass spectroscopy (GC-MS) data confirmed the different metabolic fate of these structurally unidentical dyes. FTIR and HPTLC analysis of extracted metabolites confirmed the biodegradation, while phytotoxicity study assured the detoxification of both the dyes studied. The results obtained in this study suggests, i) sulpho and hydroxyl group present at ortho position to azo group stimulated reduction of azo bond by azo reductase in Remazol red, ii) the same reduction was totally hampered due to presence of ethyl-amino propanenitrile group at para position to azo group in Rubine GFL.

The role of Aster amellus Linn. in the degradation of a sulfonated azo dye Remazol Red: a phytoremediation strategy.

Phytoremediation is a novel and promising approach for the treatment of pollutants. This study did explore the potential of Aster amellus Linn. to decolorize a sulfonated azo dye Remazol Red (RR), a mixture of dyes and a textile effluent. Induction in the activities of lignin peroxidase, tyrosinase, veratryl alcohol oxidase and riboflavin reductase was observed during RR decolorization, suggesting their involvement in the metabolism of RR. UV-Visible absorption spectrum, HPLC and FTIR analysis confirmed the degradation of RR. Four metabolites after the degradation of the dye were identified as 2-[(3-diazenylphenyl) sulfonyl] ethanesulfonate, 4-amino-5-hydroxynaphthalene-2,7-disulfonate, naphthalene-2-sulfonate and 3-(1,3,5-triazin-2-ylamino)benzenesulfonate by using GC/MS. Textile effluent and mixture of dyes showed 47% and 62% decrease respectively in American Dye Manufacturers Institute value. BOD of textile effluent and mixture of dyes were reduced by 75% and 48% respectively, COD of industrial effluent and mixture of dyes was reduced by 60% and 75% and TOC was reduced by 54% and 69% respectively after the treatment by A. amellus for 60 h; this indicated that the plant can be used for cleaning textile effluents. Toxicity study revealed the phytotransformation of RR into non-toxic products.

Efficient industrial dye decolorization by Bacillus sp. VUS with its enzyme system.

This work presents role of different enzymes in decolorization of industrial dye Orange T4LL by Bacillus sp. VUS. Bacillus sp. strain VUS decolorized dye Orange T4LL, under static anoxic condition in 24 h. During decolorization of Orange T4LL a significant induction in the activities of lignin peroxidase, tyrosinase, and reductases (NADH-DCIP, azo, and riboflavin) was observed. The biodegradation was monitored by Ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and high performance liquid chromatography. The final products 4-methyl-2-o-tolylazo-benzene-1,3-diamine and [3-(phenyl-hydrazono)-cyclohexa-1,4-dienyl]-methanol were characterized by gas chromatography-mass spectroscopy. Phytotoxicity, COD, and BOD revealed non-toxicity of degraded products. Phytotoxicity study demonstrated non-toxicity of the biodegraded products for crop plants with respect to Triticum aestivum and Sorghum bicolor. Bacillus sp. VUS with its enzyme system could be a useful tool for textile effluent treatment.

Exploring the ability of Sphingobacterium sp. ATM to degrade textile dye Direct Blue GLL, mixture of dyes and textile effluent and production of polyhydroxyhexadecanoic acid using waste biomass generated after dye degradation.

The degradation of textile effluent using microorganisms has been studied extensively, but disposal of generated biomass after dye degradation is a serious problem. Among all tested microorganisms, isolated Sphingobacterium sp. ATM effectively decolorized (100%) the dye Direct Blue GLL (DBGLL) and simultaneously it produced (64%) polyhydroxyhexadecanoic acid (PHD). The organism decolorized DBGLL at 300 mg l(-1) concentration within 24 h of dye addition and gave optimum production of PHD. The organism also decolorized three combinations of mixture of dyes. The organism decolorized textile effluent too when it was combined with medium. The organism produced a maximum of 66% and 61% PHD while decolorizing mixture of dyes and textile effluent respectively. Molasses was found to be more significant within all carbon sources used. The activity of polyhydroxyalkanoate (PHA) synthase was found to be higher after 24 h of addition of DBGLL. The enzymes responsible for dye degradation, viz. veratryl alcohol oxidase, laccase, DCIP (2,6-dichlorophenol-indophenol) reductase, riboflavin reductase, and azo reductase were found to be induced during decolorization process of DBGLL and mixture of dyes. There was significant reduction in chemical oxygen demand (COD) and biological oxygen demand (BOD). FTIR analysis of samples before and after decolorization of dye confirmed the biotransformation of DBGLL.

Decolorization and detoxification of Congo red and textile industry effluent by an isolated bacterium Pseudomonas sp. SU-EBT.

The 16S rRNA sequence and biochemical characteristics revealed the isolated organism as Pseudomonas sp. SU-EBT. This strain showed 97 and 90% decolorization of a recalcitrant dye, Congo red (100 mg l(-1)) and textile industry effluent with 50% reduction in COD within 12 and 60 h, respectively. The optimum pH and temperature for the decolorization was 8.0 and 40 degrees C, respectively. Pseudomonas sp. SU-EBT was found to tolerate the dye concentration up to 1.0 g l(-1). Significant induction in the activity of intracellular laccase suggested its involvement in the decolorization of Congo red. The metabolites formed after decolorization of Congo red, such as p-dihydroxy biphenyl, 8-amino naphthol 3-sulfonic acid and 3-hydroperoxy 8-nitrosonaphthol were characterized using FTIR and GC-MS. Phytotoxicity study revealed nontoxic nature of the degradation metabolites to Sorghum bicolor, Vigna radiata, Lens culinaris and Oryza sativa plants as compared to Congo red and textile industry effluent. Pseudomonas sp. SU-EBT decolorized several individual textile dyes, dye mixtures and textile industry effluent, thus it is a useful strain for the development of effluent treatment methods in textile processing industries.

Production of polyhydroxyhexadecanoic acid by using waste biomass of Sphingobacterium sp. ATM generated after degradation of textile dye Direct Red 5B.

The degradation of textile effluent using microorganisms has been studied extensively, but disposal of generated biomass after dye degradation is a serious problem. The isolated Sphingobacterium sp. ATM was found to decolorize dye Direct Red 5B (DR5B) and simultaneously it produced polyhydroxyhexadecanoic acid (PHD). The organism decolorized DR5B at 500mgl(-1) concentration within 24h of dye addition and gave optimum production of PHD. The medium contains carbon source as a molasses which was found to be more significant within all carbon sources used. The Nuclear Magnetic Resonance spectroscopy (NMR), Fourier Transform Infrared spectroscopy (FTIR) and Gas Chromatography-Mass Spectroscopy (GC-MS) characterization of polyhydroxyalkanoates obtained revealed the compound as a polyhydroxyhexadecanoic acid. The activity of PHA synthase was found more at 24h after dye addition. The enzymes responsible for dye degradation include veratrol oxidase, laccase, DCIP (2,6-dichlorophenol-indophenol) reductase, riboflavin reductase and azo reductase was found to be induced during decolorization process. The FTIR analysis of samples before and after decolorization of dye confirmed the biotransformation of DR5B. The GC-MS analysis of product obtained led to the identification of two metabolites after biotransformation of dye as p-amino benzenesulfonic acid and naphthalene-1-ol.