Purification and characterization of a high salt-tolerant alginate lyase from Cobetia sp. WG-007.

An alginate lyase producing bacterial strain, Cobetia sp. WG-007, was isolated and identified from rotting seaweed. The alginate lyase, Aly-W02, was purified by procedures of ultrafiltration, Q-Sepharose Fast Flow, Phenyl Sepharose 6 Fast Flow, and Superdex-G100 with specific activity of 21,285.5 U/mg. Aly-W02 had an apparent molecular mass of 35 kDa. It exhibited maximum activity at 45 °C in 50 mM sodium phosphate buffer (pH 8.5). This alginate lyase was stable in the pH range of 6.0-8.5. Among the tested metal ions, the addition of K+ , Na+ , and Mg2+ ions can enhance the enzyme activities, while Ba2+ , Ni+ , Cu2+ , Mn2+ , Zn2+ , Ag+ , and ethylenediaminetetraacetic acid decreased the activities. It displayed high salt-tolerant ability; 0.8 M NaCl or 1.5 M KCl significantly enhanced the enzyme activity. Furthermore, Aly-W02 mainly released disaccharide, trisaccharide, and tetrasaccharid from alginate. It showed potential in producing low molecular weight alginate oligosaccharides.