Genome Analysis of Alginate-Degrading Bacterium Vibrio sp. 32415 and Optimization of Alginate Lyase Production

<i>Vibrio</i> sp. is one of the main producers of alginate lyase; however, most strains have problems such as low and unstable enzyme production. In this study, the enzyme production conditions of <i>V.</i> sp. 32415, a marine bacterium capable of producing extracellular alginate lyase, were optimized through Response Surface Design. The optimized medium was as follows: NaCl 12 g/L, FeSO₄·7H₂O 0.067 g/L, NH₄Cl 7 g/L, alginate 11 g/L, K₂HPO₄·3H₂O 4 g/L, MgSO₄·7H₂O 1 g/L. Under 28 °C, 160 rpm, 30 mL/300 mL liquid volume, and an initial pH 5.5 culture condition, the extracellular enzyme activity was 51.06 U/mL, which was 2.8 times higher compared with the activity before optimization. The optimal temperature, pH, and NaCl concentration for the extracellular alginate lyase were 37 °C, 8.0, and 0.1 M, respectively. The enzyme remained more than 80% of its original activity at 30 °C for 4 h. 1 mM Fe³⁺, Ca²⁺, K⁺, Mg²⁺, and Na⁺ enhance enzyme activity, with a preference for polyG blocks. <i>V.</i> sp. 32415 has two circular chromosomes and one circular plasmid. Chromosome 2 has two polysaccharide utilization loci. It utilizes alginate through the Scatter pathway. The results of this study provide theoretical and data support for understanding the production of extracellular alginate lyase by marine <i>Vibrio</i> and their metabolism and utilization of alginate.