- Email: [email protected]
Comparison of enzymatic pretreatments with three xylanases for enhancing H2O2 bleaching of wheat straw chemomechanical pulp
Abstracts / Journal of Biotechnology 136S (2008) S356–S401
ventional chemical methods, which need high energy and long time because of multistep of protection, deprotection and glycosyl activation (Car et al., 2006; Rodenko et al., 2002). Enzymatic synthesis has been applied during the last years in order to obtain pure and efficient nucleosides in a stereospecific way (Mathieu et al., 2004); however, the cost of N-deoxyribosyl transferase is the main hurdle of industrialization of 6-chloropurine riboside production. Utilizing whole cell as biocatalyst for 6-chloropurine riboside is a potential way to reduce the cost of N-deoxyribosyl transferase since it can avoid the complicated processes of isolation and purification. In our present work, it is pleased to find that the whole cell of Lactobacillus helveticus can catalyze the conversion of guanosine riboside to 6-chloropurine riboside production with a high conversion yield. Cells were batch grown, and were harvested by centrifugation after 40 h, washed and resuspended in the biotransformation medium, which contained 5 mL pH 6.0 phosphate buffer, 10 mmol/L of guanosine riboside and 30 mmol/L 6-chloropurine. The reaction was stirred at 120 rpm and 40 ◦ C. The conversion extent was measured by HPLC (Waters 510) with UV detection at 275 nm. The whole cell of Lactobacillus helveticus was proposed further to catalyze the transglycosylation and under the optimum conditions (substrate condition guanosine 10 mmol/L, 6chloropurine 30 mmol/L; pH 6.5; 30% whole cell of Lactobacillus helveticus based on substrates weight; temperature 40 ◦ C; 180 rpm and 25 h) the highest yield of 52% could be achieved.
References Car, Z., Petrovic, V., Tomic, S., 2006. Synthesis and enzymic hydrolysis of acylated adenosine derivatives. J. Carbohydr. Chem. 25, 8–10. Mathieu, R., Baurand, A., Schmitt, M., Gachet, C., 2004. Synthesis and biological activity of 2-alkylated deoxyadenosine bisphosphate derivatives as P2Y receptor antagonists. Bioorg. Med. Chem. 12, 69–79. Rodenko, B., Wanner, M.J., Koomen, G.J., 2002. Solid phase synthesis of C2,N-6disubstituted adenosine analogues. J. Chem. Phys. 10, 1247–1252.
doi:10.1016/j.jbiotec.2008.07.876
S381
ric reduction of 4-(trimethylsilyl)-3-butyn-2-one in anti-Prelog’s way and a new strain of Acetobacter sp. was screened out from Chinese kefir grain. Compared with the reported ones capable of mediating asymmetric reduction according to anti-Prelog’s rule, including Pichia farinosa GIM2.154, Aspergillus terreus GIM3.389, Emericella nidulans GIM3.394, and Lactobacillus brevis CICC20014, this newly isolated strain offered the highest yield and product e.e. for the above-mentioned reaction. To get a deeper insight into the reaction, the effects of several crucial variables on the reaction were investigated. 2-Propanol was shown to be the best co-substrate for the intracellular regeneration of the coenzyme and the optimal buffer pH, 2-propanol’s concentration, reaction temperature and substrate concentration in TEA-HCl buffer media are 5.0, 1.0% (v/v), 30 ◦ C and 6.0 mM, respectively. Under these conditions the maximum yield and product e.e. after a reaction time of 1 h can be up to 71.3% and >99.9%, respectively, which are much higher than the corresponding values previously reported.
References Lou, W.Y., Zong, M.H., Smith, T.J., 2006. Use of ionic liquids to improve whole-cell biocatalytic asymmetric reduction of acetyltrimethylsilane for efficient synthesis of enantiopure (S)-1-trimethylsilylethanol. Green Chem. 8, 147–155. Zhang, B.B., Lou, W.Y., Zong, M.H., Wu, H., 2008. Efficient synthesis of enantiopure (S)4-(trimethylsilyl)-3-butyn-2-ol via asymmetric reduction of 4-(trimethylsilyl)3-butyn-2-one with immobilized Candida parapsilosis CCTCC M203011 cells. J. Mol. Catal. B: Enzym. 54, 122–129.
doi:10.1016/j.jbiotec.2008.07.877 V3-P-070 Comparison of enzymatic pretreatments with three xylanases for enhancing H2 O2 bleaching of wheat straw chemomechanical pulp Feng Hong
V3-P-068
Group of Microbiological Engineering and Industrial Biotechnology, Institute of Biological Sciences and Biotechnology, Donghua University, Shanghai 201620, China
Efficient microbial asymmetric reduction of 4-(trimethylsilyl)3-butyn-2-one
E-mail address: [email protected].
Min-Hua Zong 1,∗ , Zi-Jun Xiao 1,2 , Liang Peng 1 1
Laboratory of Applied Biocatalysis, South China University of Technology, Guangzhou 510640, China 2 Department of Food Science and Engineering, Shaoguan University, Shaoguan 512005, China E-mail address: [email protected] (M.-H. Zong). Enantiopure organosilicon compounds not only play an important part in asymmetric synthesis and functional materials, but also many of them are bioactive and serve as drugs with greater pharmaceutical activity, higher selectivity and lower toxicity than their carbon counterparts. As a result, their preparation is attracting more and more attention. Particularly, the biocatalytic asymmetric reduction of silicon-containing ketones to enantiopure organosilyl alcohols has been studied extensively. In comparison with isolated enzymes, whole microbial cells are preferred to avoid the need for enzyme purification and addition or complicated extra regeneration of the coenzyme (Lou et al., 2006). However, few of the strains proved to catalyze the reductions following the anti-Prelog’s rule. For efficient preparation of (R)-4-(trimethylsilyl)-3-butyn-2-ol, a crucial intermediate for the synthesis of 5-lipoxygenase inhibitors (Zhang et al., 2008), several dozens of strains of bacteria, yeasts and moulds were examined for their potential to catalyze the asymmet-
Wheat straw is an important and abundant raw material for the pulp and paper industry, particularly in China and India. It has been concluded that there would be too heavy environmental pollution when wheat straw pulp was produced by only chemical methods. The reason why the wheat straw chemical pulp is not environmentally friendly is attributed to its own inherent characters, high SiO2 content and many low molecular weight polysaccharides, resulting in problems in the chemical recovery process. However, the difficulty could be overcome partially with chemomechanical pulping (CMP) methods. Presently, the problem associated with wheat straw CMP is low brightness, approximately only 30–50% ISO, even when medium pulp concentration and 12% hydrogen peroxide is used. This limits the utilization of the pulp. So till now, wheat straw CMP is only employed to produce corrugated paper and cardboard, whose additional value is low. The objective of this research was to implement xylanase pretreatment to enhance the effect of H2 O2 bleaching of wheat straw CMP and to select a suitable enzyme for future industrial use. Our previous study has showed that pretreatment by a xylanase from Trichoderma reesei Rut C-30 improved the bleachability of wheat straw CMP considerably, increased the brightness effectively as well as decreased the noneffective consumption of the bleach agent H2 O2 (Hong et al., 2001). The achieved satisfactory results with xylanase pretreatment of wheat straw CMP may facilitate the utilization of wheat straw for pulping. In this
S382
Abstracts / Journal of Biotechnology 136S (2008) S356–S401
study, effects of pretreatments of three types of xylanase from T. reesei, T. viride, and Pseudomonas fluorescence on brightness and physical properties of wheat straw CMP after H2 O2 bleaching were investigated and compared. Changes in appearance of CMP fiber were inspected using scanning electron microscope. The result indicated that pretreatment using xylanase from the bacterium P. fluorescence was better than the others. Acknowledgements Project 30671650, with support from the National Natural Science Foundation of China and the Program for Changjiang Scholars and Innovative Research Team in University (IRT0526) are gratefully acknowledged. Reference Hong, F., Liu, M., Fang, G., Shen, Z., 2001. Enzymatic pretreatment with xylanase for improving bleachability and brightness of wheat straw chemomechanical pulp. Chemistry and Industry of Forest Products (Linchan Huaxue Yu Gongye) 21 (1), 21–28.
containing hydrophilic amino acids, while for hydrophilic dyestuffs, the situation reversed. Acknowledgements The Cultivation Fund of Key Laboratory of Science & Technology of Eco-Textile, Donghua University, Ministry of Education and the Program for Changjiang Scholars and Innovative Research Team in University (IRT0526) are gratefully acknowledged. References Aydin, A.H., Tez, Z., 2003. The sorption behaviors between natural dyes and wool fibre. Int. J. Chem. 13, 85–91. Na, Y., Lee, E.S., 2003. Handle and dyeability of wool fabrics bleached with protease. J. Korean Fiber Soc. 40, 164–169. Riva, A., Algaba, I., Prieto, R., 2002. Dyeing kinetics of wool fabrics pretreated with a protease. Color. Technol. 118, 59–63.
doi:10.1016/j.jbiotec.2008.07.879 V3-P-072
doi:10.1016/j.jbiotec.2008.07.878
Laccase immobilization into mesoporous silica materials and its stability and catalytic properties
V3-P-071
Yan Wang 1,∗ , Min Zhao 2 , Xu-han Zheng 1
Enhancement of the natural dyestuff dyeability of wool fabrics with protease pretreatment Wenhong Cheng 1 , Qicheng Zhou 1 , Qinhua Yuan 2 , Feng Hong 2,∗ 1
College of Textile, Donghua University, Shanghai 201620, China Key Laboratory of Science & Technology of Eco-Textile, Donghua University, Ministry of Education, Shanghai 201620, China 2
E-mail address: [email protected] (F. Hong). Recently, environmental problems with the synthetic dyestuffs have becoming serious and people are paying more attention to their health care. Therefore it is worthy of turning back to dyeing with natural dyestuffs, which are not toxic to people and environment, to get more “green” and healthy textile products. Several research results with respect to dyeing of wool with natural dyes have been reported during these years (Aydin and Tez, 2003). Natural dyestuffs are reproducible, environmentally friendly and some kinds of natural dyestuffs are antibacterial and hygienical, which have advantages in sustainable development in long views. However, they also have some shortcomings, such as poor color fastness and unevenness, resulting in that most markets are occupied by synthetic dyestuffs nowadays. The application of proteases on wool fabrics has showed increased dyeability with synthetic dyes (Riva et al., 2002) and improved finishing effects, softer touch and better handle (Na and Lee, 2003). In order to promote the application of natural dyes to substitute problematic synthetic dyes in future, the enzymatic pretreatments of wool fabrics with three different types of proteases to improve the dyeing effects of natural dyestuffs were investigated. Enzymatic pretreatments with the three kinds of proteases led to a faster rate of dyeing, increased dye uptake, improved K/S values as well as significantly increased dye exhaustion, resulting in an enhanced wool dyeability with several favorable effects: deeper color, lower dyeing temperature and dyestuff saving. For hydrophilic and hydrophobic types of natural dyestuffs, it was very important to choose a proper protease to pretreat wool from many different kinds of proteases (such as trypsin and papain) with different specificities in order to achieve much better dyeability at lower temperature. For hydrophobic dyestuffs, it was better to choose the proteases, which prefer to catalyze the hydrolysis of the protein
1
Science Research Center, Harbin Institute of Technology, Harbin 150001, China 2 College of Life Sciences, Northeast Forestry University, Harbin 150040, China E-mail address: wangy [email protected] (Y. Wang).
Recently developed ordered mesoporous silicas which have large surface area, uniform sized pores are interesting solids for enzyme immobilization (Pandya et al., 2005; Aburto et al., 2005). Laccase is a multicopper oxidase which catalyzes the oxidation of a broad range of substrates and can be used in bioremediation, paperpulp bleaching and decolorization of synthetic dyes (Wan et al., 2006). In this study mesoporous silica materials MCM-41, SBA15 and meso-cellular foams (MCF) were prepared and employed as the supports for laccase immobilization. These materials possessed an average pore size of 4.26, 5.27 and 8.82 nm and a BET surface of 1042, 881 and 757m2 /g, respectively. Laccase was loaded into the supports by physical adsorption. The loading time, pH and amount of enzyme provided were investigated and it was found that the immobilization processes were influenced by the pore structure and surface charge of the supports. The enzymatic properties including the optimum working pH, temperature and stability of immobilized enzymes were also studied. It showed that the immobilized laccases were stable in wider pH range and kept higher relative activities after storing at different temperature. The immobilized enzymes could be used repeatedly and the remained relative activities were between 40 and 50% after reaction with 2,2 azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) of 10 times. The immobilized enzymes were used for dye decolorization. For Congo-red solution of 100 mg/L, the decolorization ratio could be above 98% within 2 h by immobilized laccases of all the supports. The results indicate that mesoporous silicas can be used as novel support materials for laccase immobilization and are favorable to the improvement on the stability and practicality of laccase. References Aburto, J., Ayala, M., Bustos-Jaimes, J., et al., 2005. Stability and catalytic properties of chloroperoxidase immobilized on SBA-16 mesoporous materials. Micropor. Mesopor. Mater. 83, 193–200.
ventional chemical methods, which need high energy and long time because of multistep of protection, deprotection and glycosyl activation (Car et al., 2006; Rodenko et al., 2002). Enzymatic synthesis has been applied during the last years in order to obtain pure and efficient nucleosides in a stereospecific way (Mathieu et al., 2004); however, the cost of N-deoxyribosyl transferase is the main hurdle of industrialization of 6-chloropurine riboside production. Utilizing whole cell as biocatalyst for 6-chloropurine riboside is a potential way to reduce the cost of N-deoxyribosyl transferase since it can avoid the complicated processes of isolation and purification. In our present work, it is pleased to find that the whole cell of Lactobacillus helveticus can catalyze the conversion of guanosine riboside to 6-chloropurine riboside production with a high conversion yield. Cells were batch grown, and were harvested by centrifugation after 40 h, washed and resuspended in the biotransformation medium, which contained 5 mL pH 6.0 phosphate buffer, 10 mmol/L of guanosine riboside and 30 mmol/L 6-chloropurine. The reaction was stirred at 120 rpm and 40 ◦ C. The conversion extent was measured by HPLC (Waters 510) with UV detection at 275 nm. The whole cell of Lactobacillus helveticus was proposed further to catalyze the transglycosylation and under the optimum conditions (substrate condition guanosine 10 mmol/L, 6chloropurine 30 mmol/L; pH 6.5; 30% whole cell of Lactobacillus helveticus based on substrates weight; temperature 40 ◦ C; 180 rpm and 25 h) the highest yield of 52% could be achieved.
References Car, Z., Petrovic, V., Tomic, S., 2006. Synthesis and enzymic hydrolysis of acylated adenosine derivatives. J. Carbohydr. Chem. 25, 8–10. Mathieu, R., Baurand, A., Schmitt, M., Gachet, C., 2004. Synthesis and biological activity of 2-alkylated deoxyadenosine bisphosphate derivatives as P2Y receptor antagonists. Bioorg. Med. Chem. 12, 69–79. Rodenko, B., Wanner, M.J., Koomen, G.J., 2002. Solid phase synthesis of C2,N-6disubstituted adenosine analogues. J. Chem. Phys. 10, 1247–1252.
doi:10.1016/j.jbiotec.2008.07.876
S381
ric reduction of 4-(trimethylsilyl)-3-butyn-2-one in anti-Prelog’s way and a new strain of Acetobacter sp. was screened out from Chinese kefir grain. Compared with the reported ones capable of mediating asymmetric reduction according to anti-Prelog’s rule, including Pichia farinosa GIM2.154, Aspergillus terreus GIM3.389, Emericella nidulans GIM3.394, and Lactobacillus brevis CICC20014, this newly isolated strain offered the highest yield and product e.e. for the above-mentioned reaction. To get a deeper insight into the reaction, the effects of several crucial variables on the reaction were investigated. 2-Propanol was shown to be the best co-substrate for the intracellular regeneration of the coenzyme and the optimal buffer pH, 2-propanol’s concentration, reaction temperature and substrate concentration in TEA-HCl buffer media are 5.0, 1.0% (v/v), 30 ◦ C and 6.0 mM, respectively. Under these conditions the maximum yield and product e.e. after a reaction time of 1 h can be up to 71.3% and >99.9%, respectively, which are much higher than the corresponding values previously reported.
References Lou, W.Y., Zong, M.H., Smith, T.J., 2006. Use of ionic liquids to improve whole-cell biocatalytic asymmetric reduction of acetyltrimethylsilane for efficient synthesis of enantiopure (S)-1-trimethylsilylethanol. Green Chem. 8, 147–155. Zhang, B.B., Lou, W.Y., Zong, M.H., Wu, H., 2008. Efficient synthesis of enantiopure (S)4-(trimethylsilyl)-3-butyn-2-ol via asymmetric reduction of 4-(trimethylsilyl)3-butyn-2-one with immobilized Candida parapsilosis CCTCC M203011 cells. J. Mol. Catal. B: Enzym. 54, 122–129.
doi:10.1016/j.jbiotec.2008.07.877 V3-P-070 Comparison of enzymatic pretreatments with three xylanases for enhancing H2 O2 bleaching of wheat straw chemomechanical pulp Feng Hong
V3-P-068
Group of Microbiological Engineering and Industrial Biotechnology, Institute of Biological Sciences and Biotechnology, Donghua University, Shanghai 201620, China
Efficient microbial asymmetric reduction of 4-(trimethylsilyl)3-butyn-2-one
E-mail address: [email protected].
Min-Hua Zong 1,∗ , Zi-Jun Xiao 1,2 , Liang Peng 1 1
Laboratory of Applied Biocatalysis, South China University of Technology, Guangzhou 510640, China 2 Department of Food Science and Engineering, Shaoguan University, Shaoguan 512005, China E-mail address: [email protected] (M.-H. Zong). Enantiopure organosilicon compounds not only play an important part in asymmetric synthesis and functional materials, but also many of them are bioactive and serve as drugs with greater pharmaceutical activity, higher selectivity and lower toxicity than their carbon counterparts. As a result, their preparation is attracting more and more attention. Particularly, the biocatalytic asymmetric reduction of silicon-containing ketones to enantiopure organosilyl alcohols has been studied extensively. In comparison with isolated enzymes, whole microbial cells are preferred to avoid the need for enzyme purification and addition or complicated extra regeneration of the coenzyme (Lou et al., 2006). However, few of the strains proved to catalyze the reductions following the anti-Prelog’s rule. For efficient preparation of (R)-4-(trimethylsilyl)-3-butyn-2-ol, a crucial intermediate for the synthesis of 5-lipoxygenase inhibitors (Zhang et al., 2008), several dozens of strains of bacteria, yeasts and moulds were examined for their potential to catalyze the asymmet-
Wheat straw is an important and abundant raw material for the pulp and paper industry, particularly in China and India. It has been concluded that there would be too heavy environmental pollution when wheat straw pulp was produced by only chemical methods. The reason why the wheat straw chemical pulp is not environmentally friendly is attributed to its own inherent characters, high SiO2 content and many low molecular weight polysaccharides, resulting in problems in the chemical recovery process. However, the difficulty could be overcome partially with chemomechanical pulping (CMP) methods. Presently, the problem associated with wheat straw CMP is low brightness, approximately only 30–50% ISO, even when medium pulp concentration and 12% hydrogen peroxide is used. This limits the utilization of the pulp. So till now, wheat straw CMP is only employed to produce corrugated paper and cardboard, whose additional value is low. The objective of this research was to implement xylanase pretreatment to enhance the effect of H2 O2 bleaching of wheat straw CMP and to select a suitable enzyme for future industrial use. Our previous study has showed that pretreatment by a xylanase from Trichoderma reesei Rut C-30 improved the bleachability of wheat straw CMP considerably, increased the brightness effectively as well as decreased the noneffective consumption of the bleach agent H2 O2 (Hong et al., 2001). The achieved satisfactory results with xylanase pretreatment of wheat straw CMP may facilitate the utilization of wheat straw for pulping. In this
S382
Abstracts / Journal of Biotechnology 136S (2008) S356–S401
study, effects of pretreatments of three types of xylanase from T. reesei, T. viride, and Pseudomonas fluorescence on brightness and physical properties of wheat straw CMP after H2 O2 bleaching were investigated and compared. Changes in appearance of CMP fiber were inspected using scanning electron microscope. The result indicated that pretreatment using xylanase from the bacterium P. fluorescence was better than the others. Acknowledgements Project 30671650, with support from the National Natural Science Foundation of China and the Program for Changjiang Scholars and Innovative Research Team in University (IRT0526) are gratefully acknowledged. Reference Hong, F., Liu, M., Fang, G., Shen, Z., 2001. Enzymatic pretreatment with xylanase for improving bleachability and brightness of wheat straw chemomechanical pulp. Chemistry and Industry of Forest Products (Linchan Huaxue Yu Gongye) 21 (1), 21–28.
containing hydrophilic amino acids, while for hydrophilic dyestuffs, the situation reversed. Acknowledgements The Cultivation Fund of Key Laboratory of Science & Technology of Eco-Textile, Donghua University, Ministry of Education and the Program for Changjiang Scholars and Innovative Research Team in University (IRT0526) are gratefully acknowledged. References Aydin, A.H., Tez, Z., 2003. The sorption behaviors between natural dyes and wool fibre. Int. J. Chem. 13, 85–91. Na, Y., Lee, E.S., 2003. Handle and dyeability of wool fabrics bleached with protease. J. Korean Fiber Soc. 40, 164–169. Riva, A., Algaba, I., Prieto, R., 2002. Dyeing kinetics of wool fabrics pretreated with a protease. Color. Technol. 118, 59–63.
doi:10.1016/j.jbiotec.2008.07.879 V3-P-072
doi:10.1016/j.jbiotec.2008.07.878
Laccase immobilization into mesoporous silica materials and its stability and catalytic properties
V3-P-071
Yan Wang 1,∗ , Min Zhao 2 , Xu-han Zheng 1
Enhancement of the natural dyestuff dyeability of wool fabrics with protease pretreatment Wenhong Cheng 1 , Qicheng Zhou 1 , Qinhua Yuan 2 , Feng Hong 2,∗ 1
College of Textile, Donghua University, Shanghai 201620, China Key Laboratory of Science & Technology of Eco-Textile, Donghua University, Ministry of Education, Shanghai 201620, China 2
E-mail address: [email protected] (F. Hong). Recently, environmental problems with the synthetic dyestuffs have becoming serious and people are paying more attention to their health care. Therefore it is worthy of turning back to dyeing with natural dyestuffs, which are not toxic to people and environment, to get more “green” and healthy textile products. Several research results with respect to dyeing of wool with natural dyes have been reported during these years (Aydin and Tez, 2003). Natural dyestuffs are reproducible, environmentally friendly and some kinds of natural dyestuffs are antibacterial and hygienical, which have advantages in sustainable development in long views. However, they also have some shortcomings, such as poor color fastness and unevenness, resulting in that most markets are occupied by synthetic dyestuffs nowadays. The application of proteases on wool fabrics has showed increased dyeability with synthetic dyes (Riva et al., 2002) and improved finishing effects, softer touch and better handle (Na and Lee, 2003). In order to promote the application of natural dyes to substitute problematic synthetic dyes in future, the enzymatic pretreatments of wool fabrics with three different types of proteases to improve the dyeing effects of natural dyestuffs were investigated. Enzymatic pretreatments with the three kinds of proteases led to a faster rate of dyeing, increased dye uptake, improved K/S values as well as significantly increased dye exhaustion, resulting in an enhanced wool dyeability with several favorable effects: deeper color, lower dyeing temperature and dyestuff saving. For hydrophilic and hydrophobic types of natural dyestuffs, it was very important to choose a proper protease to pretreat wool from many different kinds of proteases (such as trypsin and papain) with different specificities in order to achieve much better dyeability at lower temperature. For hydrophobic dyestuffs, it was better to choose the proteases, which prefer to catalyze the hydrolysis of the protein
1
Science Research Center, Harbin Institute of Technology, Harbin 150001, China 2 College of Life Sciences, Northeast Forestry University, Harbin 150040, China E-mail address: wangy [email protected] (Y. Wang).
Recently developed ordered mesoporous silicas which have large surface area, uniform sized pores are interesting solids for enzyme immobilization (Pandya et al., 2005; Aburto et al., 2005). Laccase is a multicopper oxidase which catalyzes the oxidation of a broad range of substrates and can be used in bioremediation, paperpulp bleaching and decolorization of synthetic dyes (Wan et al., 2006). In this study mesoporous silica materials MCM-41, SBA15 and meso-cellular foams (MCF) were prepared and employed as the supports for laccase immobilization. These materials possessed an average pore size of 4.26, 5.27 and 8.82 nm and a BET surface of 1042, 881 and 757m2 /g, respectively. Laccase was loaded into the supports by physical adsorption. The loading time, pH and amount of enzyme provided were investigated and it was found that the immobilization processes were influenced by the pore structure and surface charge of the supports. The enzymatic properties including the optimum working pH, temperature and stability of immobilized enzymes were also studied. It showed that the immobilized laccases were stable in wider pH range and kept higher relative activities after storing at different temperature. The immobilized enzymes could be used repeatedly and the remained relative activities were between 40 and 50% after reaction with 2,2 azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) of 10 times. The immobilized enzymes were used for dye decolorization. For Congo-red solution of 100 mg/L, the decolorization ratio could be above 98% within 2 h by immobilized laccases of all the supports. The results indicate that mesoporous silicas can be used as novel support materials for laccase immobilization and are favorable to the improvement on the stability and practicality of laccase. References Aburto, J., Ayala, M., Bustos-Jaimes, J., et al., 2005. Stability and catalytic properties of chloroperoxidase immobilized on SBA-16 mesoporous materials. Micropor. Mesopor. Mater. 83, 193–200.