Efficient degradation of the polysaccharide extracted from Enteromorpha prolifera by using a novel polysaccharide lyase family 28 enzyme with high activity

The polysaccharides originated from Enteromorpha species exhibited versatile physiological activities and great potential in food and medicine industries. The oligosaccharides, which prepared from polysaccharide by enzymatic hydrolysis, retained the excellent activity as polysaccharide, and then revealed better solubility, bioavailability and effectiveness. However, there are few reports on Enteromorpha polysaccharide (EP)-degrading enzymes for efficient degradation of EP and high-valued utilization of Enteromorpha biomass. Herein, a novel EP-degrading enzyme, EPD1, was identified and heterologously expressed. It could efficiently hydrolyze the EP with high activity (985.755 U/mg) and exhibited optimal activity at 50 °C and a pH of 10.0. The K_m value of EPD1 was 7.5512 mg·mL⁻¹ and the V_max value was 4.9109 μmol·min⁻¹·mL⁻¹. Furthermore, EPD1 demonstrated cold adaptation as evidenced by minimal activity loss following incubation at temperatures below 30 °C for 1 h. HPLC and ESI-MS analysis revealed that EPD1 could produce disaccharides, trisaccharides and tetrasaccharides as the final degradation products from EPs. In conclusion, a novel EP-degrading enzyme with high activity and excellent performance was identified and it can expand the database of EP-degrading enzymes and provide the possibility to make full use of EPs.