Purification and characterization of a novel enzyme produced by Catenovulum sp. LP and its application in the pre-treatment to Ulva prolifera for bio-ethanol production

• A novel depolymerase to degrade PU was reported.
• The depolymerase degraded PU efficiently, which also declined the viscosity of PU noticeably.
• The enzymatic hydrolysis of PU was first reported.

The high viscosity of polysaccharides from Ulva prolifera (PU) is one reason that impeded the high production of bio-ethanol by U. prolifera. A depolymerase with high specificity was first isolated from Catenovulum sp. LP. The 75.5 kDa depolymerase was purified 42.35-fold to homogeneity with 22.86 U/mg specific activity. The enzyme showed the highest activity at the optimal conditions of pH 6.0 and 35 °C. It also showed high stability with a Half-life (t1/2) of 1386 min at 35 °C. It retained 100% of its residual activity in 10 mM EDTA, 1,10-phenanthrolin, or Tween 80 after incubation of 2 h. The depolymerase showed high efficiency to PU for reducing sugar production, which reached 50.2% yield in 6 h. However, the commercial enzymes showed no hydrolysis to PU. The viscosity of 1.2% PU noticeable declined from initially 1127 to 7.2 mPa s in 95 min of hydrolysis even in the room temperature. The application of depolymerase with these unique properties could bring promising prospects for enzymatic pretreatment of the bio-ethanol production from U. prolifera biomass.