A Novel Alkaliphilic Xylanase from the Newly Isolated Mesophilic Bacillus sp. MX47: Production, Purification, and Charac
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A Novel Alkaliphilic Xylanase from the Newly Isolated Mesophilic Bacillus sp. MX47: Production, Purification, and Characterization Won-Jae Chi & Da Yeon Park & Yong-Keun Chang & Soon-Kwang Hong
Received: 20 April 2012 / Accepted: 3 August 2012 # Springer Science+Business Media, LLC 2012
Abstract A newly isolated bacterial strain, Bacillus sp. MX47, was actively producing extracellular xylanase only in xylan-containing medium. The xylanase was purified from the culture broth by two chromatographic steps. The xylanase had an apparent molecular weight of 26.4 kDa with an NH2-terminal sequence (Gln-Gly-Gly-Asn-Phe) distinct from that of reported proteins, implying it is a novel enzyme. The optimum pH and temperature for xylanase activity were 8.0 and 40 °C, respectively. The enzyme activity was severely inhibited by many divalent metal ions and EDTA at 5 mM. The xylanase was highly specific to beechwood and oat spelt xylan, however, not active on carboxymethyl cellulose (CMC), avicel, pectin, and starch. Analysis of the xylan hydrolysis products by Bacillus sp. MX47 xylanase indicated that it is an endo-β-1,4-xylanase. It hydrolyzed xylan to xylobiose as the end product. The Km and Vmax values toward beechwood xylan were 3.24 mgml−1 and 58.21 μmolmin−1 mg−1 protein, respectively. Keywords Xylanase . Endo-β-1,4-xylanase . Xylobiose . Bacillus sp. . Purification . Chromatography
Introduction Xylan is a generic term used to describe a wide variety of highly complex polysaccharides composed of xylose units that are found in the cell walls of most plant and algal species. It constitutes 20–40 % of total plant biomass, making it the second most abundant natural biopolymer after cellulose and a major hemicellulosic component. Therefore, efficient xylan Won-Jae Chi and Da Yeon Park contributed equally for this paper. Electronic supplementary material The online version of this article (doi:10.1007/s12010-012-9828-z) contains supplementary material, which is available to authorized users. W.-J. Chi : D. Y. Park : S.-K. Hong (*) Department of Biological Science, Myongji University, Yongin, Gyeonggido 449-728, South Korea e-mail: [email protected] Y.-K. Chang Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea
Appl Biochem Biotechnol
degradation is an important prerequisite step in the utilization of the abundantly available lignocellulosic material in nature. Xylan hydrolysis can be applied in many industries, e.g., textiles, paper, and pulp industries. Moreover, the products of xylan hydrolysis, such as xylooligosaccharides and D-xylose, have enormous biotechnical potential as food additives and energy sources [7]. Xylan can be hydrolyzed by enzymatic or chemical treatment. However, enzymatic hydrolysis by xylanase is more favorable than chemical hydrolysis because it avoids potentially severe environmental problems [2]. Xylanase degrades the xylan backbone, which is composed of xylose residues linked by β-1,4-glycosidic bonds, into xylooligo
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