Characterization of an extracellular biofunctional alginate lyase from marine Microbulbifer sp. ALW1 and antioxidant activity of enzymatic hydrolysates

• Published in: Microbiological research Vol. 182; pp. 49 - 58
• Main Authors: Zhu, Yanbing, Wu, Liyun, Chen, Yanhong, Ni, Hui, Xiao, Anfeng, Cai, Huinong
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 01.01.2016
• Subjects: Alginate lyase; Alginate oligosaccharides; Alginates - metabolism; Antioxidant activity; Antioxidants - chemistry; Antioxidants - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Characterization; Enzyme Stability; Gammaproteobacteria - classification; Gammaproteobacteria - enzymology; Gammaproteobacteria - genetics; Gammaproteobacteria - isolation & purification; Glucuronic Acid - metabolism; Hexuronic Acids - metabolism; Hydrogen-Ion Concentration; Microbulbifer sp; Molecular Sequence Data; Molecular Weight; Phylogeny; Polysaccharide-Lyases - chemistry; Polysaccharide-Lyases - genetics; Polysaccharide-Lyases - metabolism; Seawater - microbiology; Substrate Specificity; Temperature; Characterization; Alginate lyase; Microbulbifer sp; Alginate oligosaccharides; Antioxidant activity
• ISSN: 0944-5013; 1618-0623
• DOI: 10.1016/j.micres.2015.09.004

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 26.0kDa 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.