title: Enhanced bio-catalytic performance and dye degradation potential of chitosan-encapsulated horseradish peroxidase in a packed bed reactor system.
abstract: In this study, horseradish peroxidase (HRP) was immobilized onto chitosan beads by entrapment method and employed for the degradation of textile dyes. Stable and firm quality chitosan beads developed with 2.5% chitosan concentration exhibited maximum immobilization yield (~92.54±2.53%). The pH optimum of chitosan-immobilized HRP (CTS-HRP) was marginally displaced towards alkaline region (pH7.5) than that of F-HRP which displayed its optimum activity at pH7.0. The free HRP (F-HRP) and CTS-HRP enzyme presented their maximum catalytic activities at 30°C and 70°C, respectively. Relative activities of F-HRP and CTS-HRP were decreased following pre-incubation above 30°C and 50°C, respectively and after 120min at 70°C, the F-HRP, and CTS-HRP retained 19.3±1.3 and 48.3±2.4% activities, accordingly. The CTS-HRP exhibited remarkably better resistance towards heavy metal induced activity inhibition. The effect of potential inhibitors on the activity of F-HRP and CTS-HRP was investigated and found that CTS-HRP was significantly less vulnerable to the denaturation caused by urea, ethylenediaminetetraacetic acid (EDTA), cysteine, 1, 4-dithiothreitol and Triton X-100. Moreover, the CTS-assisted entrapped-HRP was also employed for the decolorization of four different textile dyes i.e. Remazol Brilliant Blue R (RBBR), Reactive Black 5 (RB5), Congo Red (CR) and Crystal Violet (CV). The CTS-HRP showed considerable decolorization efficacy in six consecutive batch operations. Results suggest that CTS-HRP is an attractive choice for use as industrial biocatalyst in larger scale bioremediation of textile dyes and effluents.
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Bilal
authors.affiliation: School of Engineering and Science, Tecnologico de Monterrey, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. CP 64849, Mexico. Electronic address: hafiz.iqbal@my.westminster.ac.uk.
authors.forename: Hafiz M N
authors.initials: HMN
authors.lastname: Iqbal
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Xuehong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D001673:Biodegradation, Environmental; D019149:Bioreactors; D002384:Catalysis; D048271:Chitosan; D004396:Coloring Agents / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006735:Horseradish Peroxidase / Q000378:metabolism*
chemical_list: D004396:Coloring Agents; D004800:Enzymes, Immobilized; D048271:Chitosan; D006735:Horseradish Peroxidase
keywords: Chitosan beads; Dye decolorization; Encapsulation; Horseradish peroxidase; Reusability; Thermo-stability