Characterization of alginate lyase and its immobilization to hydrolyze alginate

Author: Simranjeet Kaur

Kaur, Simranjeet , 2021 Characterization of alginate lyase and its immobilization to hydrolyze alginate, Flinders University, College of Medicine and Public Health

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Alginate is the most abundant polysaccharide of brown algae, which consists of two monomeric units such as β-D mannuronic acid (M) and α-L-guluronic acid (G), and these uronic acids are arranged as M-, G-, MG blocks. Alginate lyase, a polysaccharide degrading enzyme can degrade alginate by hydrolyzing glycosidic bond and produce unsaturated oligosaccharides (AOS) that have wide application in food, nutraceuticals, and pharmaceutical industry. Immobilized enzymes facilitate industrial applications owing to their stability, reusability, and cost-effectiveness. This study investigated kinetic characterization of soluble and immobilized alginate lyase on magnetic nanoparticles. Alginate lyase immobilization was achieved using glutaraldehyde as cross-linker to a magnetic nanoparticle. Scanning electron microscopy (SEM) validated structure of nanomaterial and binding to alginate lyase. Free and immobilized enzyme exhibited different temperature optima at 37 °C and 45 °C respectively. The optimum pH was shifted from 7.4 for soluble to 9 for immobilized alginate lyase, which confirms the stability of the immobilized form. The immobilized alginate lyase exhibited thermal stability at 45 °C and retained more than 60% activity after 3 h. The reusability of immobilized alginate lyase was analyzed for 8 consecutive cycles and 50% activity was recorded till 6th cycle. This study further compared the enzymatic activity of hydrolyzing alginate from various commercial sources. The soluble and immobilized enzyme demonstrated 76% and 63% of hydrolysis of raw seaweed biomass in 60 h. The immobilized enzyme demonstrated enhanced thermal and pH tolerance, extended storage stability, and reusability fulfilling proposed objectives of the study. HPLC profile exhibited monosaccharide yield with soluble (20.5%) and immobilized (17.6%) alginate lyase.

Keywords: Alginate, Alginate lyase, Alginate oligosaccharides (AOS), DNS (Dinitro salicylic acid) assay, Immobilized alginate lyase, Magnetic nanoparticle (MNP), Glutaraldehyde cross-linker

Subject: Biotechnology thesis

Thesis type: Masters
Completed: 2021
School: College of Medicine and Public Health
Supervisor: Munish Puri