Purification and Characterization of Alginate Lyase from Marine Bacterium Vibrio sp. QY101

SONG Kai, YU Wen-Gong, HAN Feng, HAN Wen-Jun, LI Jing-Bao

( Institute of Marine Drug and Food, Ocean University of China, Qingdao 266003, China )

Abstract Extracellular alginate lyase secreted by Vibrio sp. QY101, which was isolated from brown algae, was purified to homogeneity by a combination of ammonium sulfate precipitation, DEAE-Sepharose Fast Flow anion-exchange chromatography and Superdex 75 gel filtration chromatography. Its molecular mass was 39 kD as determined by SDS-PAGE analysis. The enzyme had an optimal temperature of 30 ºC for its activity, and was most active at pH 7.5. The thermal and pH stability were 0－30 ºC, and pH 6.5-8.5, respectively. The enzyme activity was stimulated by 0.5 mol/L NaCl, 1.0 mmol/L Ca²⁺ or 5.0 mmol/L Mn²⁺, and inhibited by 5.0 mmol/L Ni²⁺, 1.0 mmol/L Fe²⁺ or 1.0 mmol/L EDTA. Preliminary analysis on substrate specificity showed that this alginate lyase had activity on both poly-a1,4-L-guluronate and poly-β1,4-D-mannuronate substrates.

Key words Vibrio sp.; alginate lyase; purification ; characterizayion

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