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Zhang Y.,Jiangnan University | Li X.,Jiangnan University | Li X.,Nanchang University | Hao Z.,Institute of Applied Biotechnology | And 3 more authors.
PLoS ONE | Year: 2016

For the more efficient detoxification of phenolic compounds, a promising avenue would be to develop a multi-enzyme biocatalyst comprising peroxidase, laccase and other oxidases. However, the development of this multi-enzyme biocatalyst is limited by the vulnerability of fungal laccases and peroxidases to hydrogen peroxide (H2 O2 )-induced inactivation. Therefore, H2 O2 -resistant peroxidase and laccase should be exploited. In this study, H2 O2 -stable CotA and YjqC were isolated from the outer coat of Bacillus altitudinis SYBC hb4 spores. In addition to the thermal and alkali stability of catalytic activity, CotA also exhibited a much higher H2 O2 tolerance than fungal laccases from Trametes versicolor and Trametes trogii. YjqC is a sporulation-related manganese (Mn) catalase with striking peroxidase activity for sinapic acid (SA) and sinapine (SNP). In contrast to the typical heme-containing peroxidases, the peroxidase activity of YjqC was also highly resistant to inhibition by H2 O2 and heat. CotA could also catalyze the oxidation of SA and SNP. CotA had a much higher affinity for SA than B. subtilis CotA. CotA and YjqC rendered from B. altitudinis spores had promising laccase and peroxidase activities for SA and SNP. Specifically, the B. altitudinis spores could be regarded as a multi-enzyme biocatalyst composed of CotA and YjqC. The B. altitudinis spores were efficient for catalyzing the degradation of SA and SNP in rapeseed meal. Moreover, efficiency of the spore-catalyzed degradation of SA and SNP was greatly improved by the presence of 15 mM H2 O2 . This effect was largely attributed to synergistic biocatalysis of the H2 O2 -resistant CotA and YjqC toward SA and SNP. © 2016 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Yang Y.,University of Shanghai for Science and Technology | Li H.,University of Shanghai for Science and Technology | Hou F.,University of Shanghai for Science and Technology | Hu J.,University of Shanghai for Science and Technology | And 2 more authors.
Materials Letters | Year: 2016

Flower-like ZnO/Ag nanocomposites were successfully synthesized via a simple, green and cost efficient method. In this method, the flower-like precursor was first prepared and subsequently calcined at 500 °C at 2 h. The XRD results confirmed the presence of pure wurtzite ZnO structure and metal Ag in flower-like precursor. The SEM and TEM results revealed that the obtained nanocomposites well inherited the morphology of the precursor and Ag particles deposited on the inside of the nanocomposites. The UV-vis diffuse reflection and PL spectra showed that ZnO/Ag nanocomposites exhibited tunable optical properties. Noteworthily, ZnO/Ag nanocomposites showed more efficient photocatalytic activity in the degradation of MB than that of pure ZnO under visible light irradiation. © 2016 Elsevier B.V. Source

Wang Y.-X.,Institute of Applied Biotechnology | Jin Y.-X.,Institute of Applied Biotechnology | Zhang X.-X.,Institute of Applied Biotechnology | Wu H.-G.,Institute of Applied Biotechnology | Wang X.-B.,CAS Lanzhou Institute of Chemical Physics
Mocaxue Xuebao/Tribology | Year: 2015

In order to study the variation of structure and properties in the processing of lithium complex grease, the soap fibers structure of 6 samples from the different step in the preparation process were respectively observed by scanning electron microscopy (SEM), and their physical and chemical properties were determined. Meanwhile, soap fibers structure of the grease samples from the different cooling process in the production of lithium complex grease were observed by SEM, and their physical and chemical properties were included. Based on the results, it can be concluded that in the process of high-temperature refining and cooling, lithium compound soap changed from solid to liquid, and then condensed liquid to solid state. Many complex soap crystal nucleus were formatted through this phase transition, and then grew to soap fibers, and finally formed a three-dimensional network structure. The key control procedure during the manufacturing process of lithium complex grease was the cooling step, which is beneficial to the development of a dense and uniform fiber three-dimensional network structure. Furthermore, turn kettle quenching was the most effective way. ©, 2015, Science Press. All right reserved. Source

Zhang X.,University of Shanghai for Science and Technology | Wang Y.,Institute of Applied Biotechnology | Hou F.,University of Shanghai for Science and Technology | Li H.,University of Shanghai for Science and Technology | And 3 more authors.
Applied Surface Science | Year: 2016

Flower-like Ag/ZnO samples were successfully fabricated via a simple and cost efficient method without surfactants. The morphologies, structural and optical properties of Ag/ZnO samples with various Ag content were investigated. The samples were systematically characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption-desorption isotherm, diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence spectroscopy (PL). It was found that ZnO was wurtzite phase and metallic Ag particles were wrapped by ZnO nanosheets. Compared with pure metallic Ag, the binding energy of Ag 3d for the Ag/ZnO samples distinctly shifted to the lower binding energy, which was attributed to the interaction between ZnO and Ag. With the increase of Ag content, surface plasmon absorption band of Ag/ZnO samples was obviously widened; meanwhile, PL intensity was decreased. The photocatalytic performance of Ag/ZnO samples were carried out by the degradation of methylene blue (MB) solution under visible light irradiation. The deposition of a certain amount of Ag was beneficial to the improvement of photocatalytic activity. The degradation rate of the Ag/ZnO sample with Ag/Zn ratio 1/20 was greater than fourfold times faster than that of ZnO. It was suggested that photoexcited electrons transferred from Ag to ZnO due to surface plasmon resonance (SPR), which could effectively reduce the recombination of electron-hole pairs and prolong lifetime of the electron-holes pairs, promoting the degradation efficiency. The deposition of a large amount of Ag was unfavorable for the formation of flower-like Ag/ZnO samples, and caused the decrease of specific surface area and the aggregation of Ag nanoparticles, leading to the reduction of photocatalytic performance. © 2016 Elsevier B.V. Source

Hao Z.,Institute of Applied Biotechnology | Wu H.,Institute of Applied Biotechnology | Yang M.,Institute of Applied Biotechnology | Chen J.,Institute of Applied Biotechnology | And 6 more authors.
International Journal of Molecular Sciences | Year: 2016

Two CHI genes from Chitinolyticbacter meiyuanensis SYBC-H1 encoding chitinases were identified and their protein 3D structures were predicted. According to the amino acid sequence alignment, CHI1 gene encoding 166 aa had a structural domain similar to the GH18 type II chitinase, and CHI2 gene encoding 383 aa had the same catalytic domain as the glycoside hydrolase family 19 chitinase. In this study, CHI2 chitinase were expressed in Escherichia coli BL21 cells, and this protein was purified by ammonium sulfate precipitation, DEAE-cellulose, and Sephadex G-100 chromatography. Optimal activity of CHI2 chitinase occurred at a temperature of 40 °C and a pH of 6.5. The presence of metal ions Fe3+, Fe2+, and Zn2+ inhibited CHI2 chitinase activity, while Na+ and K+ promoted its activity. Furthermore, the presence of EGTA, EDTA, and β-mercaptoethanol significantly increased the stability of CHI2 chitinase. The CHI2 chitinase was active with p-NP-GlcNAc, with the Km and Vm values of 23.0 µmol/L and 9.1 mM/min at a temperature of 37 °C, respectively. Additionally, the CHI2 chitinase was characterized as an N-acetyl glucosaminidase based on the hydrolysate from chitin. Overall, our results demonstrated CHI2 chitinase with remarkable biochemical properties is suitable for bioconversion of chitin waste. © 2016 by the authors; licensee MDPI, Basel, Switzerland. Source

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