2008 Volume 55 Issue 2 Pages 81-88
High activity of alginate lyase was produced by a marine bacterium (strain No. 1786), which was isolated from the intestinal contents of an arthropod. Strain No. 1786 was classified in the genus Pseudoalteromonas by morphological, biochemical and physiological characterization and 16S rDNA sequencing. The extracellular enzyme obtained from the culture supernatant was partially purified by diethylaminoethyl (DEAE) high-performance liquid chromatography (HPLC). The molecular mass of this enzyme was approximately 32.0 kDa on SDS-PAGE. The optimum temperature and pH of the enzyme reaction were 50°C and 7.1-7.7, respectively. The enzyme was stable up to 40°C and in the pH range 6.3-8.9. Furthermore, the enzyme activity was enhanced over 300% compared with the control level by the addition of 10 mM MgSO4, MgCl2, or CaCl2. In the enzyme reaction products, we detected peculiar peaks of unsaturated oligosaccharides on DEAE-HPLC derived from poly-β-D-mannuronate (PM) and poly-α-L-guluronate (PG) rich substrates, respectively. These results indicate that we have isolated a new extracellular alginate lyase in the genus Pseudoalteromonas, possessing high optimum temperature and enhancing the enzyme activity remarkably by adding Mg2+ and Ca2+.