title: Characterization of an extracellular biofunctional alginate lyase from marine Microbulbifer sp. ALW1 and antioxidant activity of enzymatic hydrolysates.
abstract: A novel alginate-degrading marine bacterium Microbulbifer sp. ALW1 was isolated from rotten brown alga. An extracellular alginate lyase was purified to electrophoretic homogeneity and had a molecular mass of about 26.0 kDa determined by SDS-PAGE and size exclusion chromatography. This enzyme showed activities towards both polyguluronate and polymannuronate indicating its bifunctionality while with preference for the former substrate. Using sodium alginate as a substrate, strain ALW1 alginate lyase was optimally active at 45 °C and pH 7.0. It was stable at 25 °C, 30 °C, 35 °C and 40 °C, but not stable at 50 °C. This alginate lyase showed good stability over a broad pH range (5.0-9.0). The enzyme activity was increased to 5.1 times by adding NaCl to a final concentration of 0.5M. Strain ALW1 alginate lyase produced disaccharide (majority) and trisaccharide from alginate indicating that this enzyme could be a good tool for preparation of alginate oligosaccharides with low degree of polymerization (DP). The alginate oligosaccharides displayed the scavenging abilities towards radicals (DPPH, ABTS(+) and hydroxyl) and the reducing power. Therefore, the hydrolysates exhibited the antioxidant activity and had potential as a natural antioxidant.
authors.affiliation: College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China.
authors.forename: Yanbing
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: College of Food and Biological Engineering, Jimei University, Xiamen 361021, China.
authors.forename: Liyun
authors.initials: L
authors.lastname: Wu
authors.affiliation: College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Ni
authors.affiliation: College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China.
authors.forename: Anfeng
authors.initials: A
authors.lastname: Xiao
authors.affiliation: College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China. Electronic address: jmswthermo@hotmail.com.
authors.forename: Huinong
authors.initials: H
authors.lastname: Cai
mesh_terms: D000464:Alginates / Q000378:metabolism; D000975:Antioxidants / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D020563:Gammaproteobacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D020723:Glucuronic Acid / Q000378:metabolism; D006603:Hexuronic Acids / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D011133:Polysaccharide-Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012623:Seawater / Q000382:microbiology*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D000464:Alginates; D000975:Antioxidants; D001426:Bacterial Proteins; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D011133:Polysaccharide-Lyases; C016158:poly(beta-D-mannuronate) lyase
keywords: Alginate lyase; Alginate oligosaccharides; Antioxidant activity; Characterization; Microbulbifer sp.