| Summary: | The aim of this study was to further broaden the heterologous expression of alginate lyase from <i>Vibrio alginolyticus</i> in a <i>Bacillus subtilis</i> expression vector. A <i>B. subtilis</i> WB600/pP43NMK-<i>alg62</i> strain was constructed. (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> precipitation and Ni-affinity chromatography were performed to purify the enzyme. We then characterized the enzyme. Its molecular weight was 57.64 kDa, and it worked optimally at 30 °C with a pH of 8.0. Ca<sup>2+</sup> markedly enhanced the enzymatic activity of Alg62 while Cu<sup>2+</sup> and Ni<sup>2+</sup> inhibited its activity. Alg62 had a wide range of substrate specificity, showing high activity toward sodium alginate and polyG. Following optimization of the fermentation process, the optimal conditions for the recombinant expression of Alg62 were as follows: temperature of 37 °C, pH of 7.0, medium consisting of glycerol 15 g/L, yeast powder 25 g/L and K<sup>+</sup> 1.5 mmol/L. At these optimal conditions, enzyme activity reached 318.21 U/mL, which was 1.54 times higher than the initial enzyme activity.
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