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Zeng X.,Jiangnan University | Cai Y.,Jiangnan University | Liao X.,Jiangnan University | Luo S.,Jiangnan University | Zhang D.,Hanbon Science and Technology Co.
Process Biochemistry | Year: 2012

A new Trametes trogii laccase was purified and its biochemical properties were subsequently characterized. After a survey of other T. trogii laccases, this laccase showed a lower isoelectric point, different N-terminal sequence and kinetic parameters. Recently most laccase-catalyzed decolorizations of synthetic dyes are single-solute studies with commercially available dyes as model pollutants and need the employment of redox mediators. In this study, to simulate the real industry wastewaters, experiments of laccase-catalyzed decolorization of mixed dyes constituted by azo and anthraquinone dyes were carried out. The results showed that anthraquinone dyes, playing the role of mediators, dramatically promoted the degradation of azo dyes when there was no exogenous mediator in the reaction mixture. This study represents the first attempt to decolorize the mixtures of azo and anthraquinone dyes by purified T. trogii laccase, suggesting great potential for laccase to decolorize textile industry wastewaters. © 2011 Elsevier Ltd. All rights reserved. Source

Zeng H.-W.,Jiangnan University | Cai Y.-J.,Jiangnan University | Liao X.-R.,Jiangnan University | Zhang F.,Jiangnan University | And 3 more authors.
Engineering in Life Sciences | Year: 2011

A high-catalase-producing strain, which was isolated from sludge containing hydrogen peroxide, was identified as Serratia marcescens SYBC08 by 16S rDNA sequence analysis. Serratia spp. was reported as non-spore-forming bacterium (except S. marcescens spp. sakuensis), but in our study electron microscopic observation revealed that the strain did produce spores. The content of the main fatty acid C16:0 (14.8%) was significantly different from that of S. marcescens spp. sakuensis (33.2%) and S. marcescens spp. marcescens DSM 30121T (34.8%), and the biochemical characteristics were not identical to those of S. marcescens spp. sakuensis. We speculate that the relatively high catalase activity and the spore structures may enable the strain to survive in a hydrogen peroxide environment. The most suitable carbon and nitrogen sources for the catalase production by S. marcescens SYBC08 were citric acid and corn steep liquor powder. A strategy of carbon metabolism regulation to enhance the catalase production was exploited. In the 7-L fermenter, catalase production (20353U/mL) obtained in the presence of glucose and citric acid was 1.68- and 1.31-fold higher than that obtained in the presence of glucose or citric acid, at equimolar carbon concentration. This production yield was much higher than that of many catalase-producing strains, but only slightly lower than the production by Micrococcus luteus (34601U/mL). The results suggest that the new spore-forming S. marcescens SYBC08 is a potential candidate for the production of catalase. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Zeng H.-W.,Jiangnan University | Cai Y.-J.,Jiangnan University | Liao X.-R.,Jiangnan University | Zhang F.,Jiangnan University | And 2 more authors.
Asian Journal of Chemistry | Year: 2011

The process of enhancing production of catalase by Serratia marcescens SYBC08 was carried out in submerged fermentation. Catalase production of critic acid induction was increased by 92 % compared to that of glucose. Statistical experimental designs were used in optimization of catalase production. Temperature, initial pH and corn steep liquor powder concentration were identified as the most significant factors by using Placket-Burman design. The optimum values of three significant factors were determined using central composite design and response surface analysis. While three optimum significant factors were revealed as temperature (32.8 °C), initial pH (5.9) and corn steep liquor powder concentration (33.8 g L-1), the maximum predicted catalase production of 11632.88 U mL-1 was calculated out using a two second-order polynomial equation. In a validate experiment, maximum catalase production of 12182.74 U mL-1 was achieved and had 28.27 % increasement compared to that under unoptimized conditions. Source

Zeng X.,Jiangnan University | Cai Y.,Jiangnan University | Liao X.,Jiangnan University | Li W.,Jiangnan University | Zhang D.,Hanbon Science and Technology Co.
Journal of Hazardous Materials | Year: 2011

A new dye-decolorizing white-rot fungus was isolated and identified as Trametes trogii based on its ITS-5.8S rRNA gene sequence analysis and morphological characteristics. Laccase was the only lignolytic enzyme produced by this strain during solid substrate fermentation (SSF) in soybean cake, a solid agro-industrial residue used for the first time in enzyme production. The extracellular crude enzyme from T. trogii in solid substrate fermentation showed good activity in synthetic dye color removal, decolorizing 85.2% Remazol Brilliant Blue R (50mgl-1), 69.6% Reactive Blue 4 (35mgl-1), and 45.6% Acid Blue 129 (83.3mgl-1) without the addition of redox mediators, 90.2% Acid Red 1 (10mgl-1), and 65.4% Reactive Black 5 (18.3mgl-1) with the addition of 1mM 1-hydroxybenzotriazole in 30min. Native polyacrylamide gel electrophoresis (Native-PAGE) of the crude enzyme and effects of laccase inhibitors on decolorization corroborated the laccase as the major enzyme involved in the decolorization of dyes. The comparison of color removal by the crude culture filtrates and by the whole fungal culture on the solid substrate revealed the former was more advantageous. © 2011 Elsevier B.V. Source

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