Abstract
An alginate lyase-producing bacterial strain, Pseudoalteromonas sp. SM0524, was screened from marine rotten kelp. In an optimized condition, the production of alginate lyase from Pseudoalteromonas sp. SM0524 reached 62.6 U/mL, suggesting that strain SM0524 is a good producer of alginate lyases. The bifunctional alginate lyase aly-SJ02 secreted by strain SM0524 was purified. Aly-SJ02 had an apparent molecular mass of 32 kDa. The optimal temperature and pH of aly-SJ02 toward sodium alginate was 50 °C and 8.5, respectively. The half life period of aly-SJ02 was 41 min at 40 °C and 20 min at 50 °C. Aly-SJ02 was most stable at pH 8.0. N-terminal sequence analysis suggested that aly-SJ02 may be an alginate lyase of polysaccharide lyase family 18. Aly-SJ02 showed activities toward both polyG (α-l-guluronic acid) and polyM (β-d-mannuronic acid), indicating that it is a bifunctional alginate lyase. Aly-SJ02 had lower Km toward polyG than toward polyM and sodium alginate. Thin layer chromatography and ESI-MS analyses showed that aly-SJ02 mainly released dimers and trimers from polyM and alginate, and trimers and tetramers from polyG, which suggests that aly-SJ02 may be a good tool to produce dimers and trimers from alginate.
Highlights
Alginate is a gelling polysaccharide found in great abundance as part of the cell wall and intracellular material in brown seaweeds (Phaeophyceae) [1]
Thin layer chromatography and ESI-MS analyses showed that aly-SJ02 mainly released dimers and trimers from polyM and alginate, and trimers and tetramers from polyG, which suggests that aly-SJ02 may be a good tool to produce dimers and trimers from alginate
Among the ten strains that were selected for their relatively bigger hydrolytic zones on the screening plates, strain 0524 had the highest rate to reduce the viscosity of the medium and the highest alginate lyase activity in its culture (Figure 1).This strain, named SM0524, was selected for further study
Summary
Alginate is a gelling polysaccharide found in great abundance as part of the cell wall and intracellular material in brown seaweeds (Phaeophyceae) [1]. Alginate is a linear hetero-polyuronic acid composed of 1,4 linked α-L-guluronic acid (G) and β-D-mannuronic acid (M). These two residues are arranged in block structures comprising homopolymeric G blocks, M blocks, alternating MG (GM). Alginate is widely used as a stabilizer, viscosifier, and gelling agent in the food and beverage, paper and printing, biomaterials, and pharmaceutical industries. Known as alginases or alginate depolymerases, catalyze the degradation of alginate by a β-elimination mechanism that has yet to be fully elucidated [1]. Alginate lyases are isolated from various sources, such as marine algae, marine mollusks, fungi, bacteria and viruses
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