Expression and characterization of three alginate lyases from <i>Vibrio</i> sp. E: targeting kelp hydrolysis and biofilm disruption

A marine bacterial strain, <i>Vibrio</i> sp. E, capable of producing alginate lyases, was isolated from seawater. Three alginate lyase genes from this strain were cloned and expressed in <i>Escherichia coli</i>. The recombinant enzymes, designated AlyE1, AlyE2, and AlyE3, exhibited optimal activity at pH 9.0 and high pH stability, retaining over 80% of their initial activity across a pH range of 6.0 to 10.0. They retained more than 50% activity at 4 °C and over 30% at 100 °C. AlyE1 and AlyE3 demonstrated thermo-tolerance, recovering the majority of of their initial activity after heat treatment (>80 °C, <120 min) and cooling (>80 °C, >10 min). All three enzymes exhibited strong NaCl tolerance but were not NaCl-dependent. They were characterized as bifunctional and endolytic lyases, which was effective in kelp (<i>Laminaria japonica</i>) hydrolysis and in disrupting <i>Pseudomonas aeruginosa</i> biofilms.