Purification and characterization of a novel β-agarase from Vibrio sp. AP-2

β-Agarase was purified from the culture fluid of a porphyran-decomposing marine bacterium (strain AP-2) by ammonium sulfate precipitation, successive column chromatography and DNase and RNase treatment. The final enzyme preparation appeared to be homogeneous on polyacrylamide gel electrophoresis. The enzyme had a molecular mass of 20 kDa, a pH optimum of 5.5, and was stable in the pH region 4.0–9.0 and at temperatures below 45°C. The β-agarase was a novel endo-type enzyme which hydrolyzed neoagarotetraose, larger neoagarooligosaccharides and agar to give neoagarobiose [3,6-anhydro-α-L-galactopyranosyl-(13)-D-galactose] as the predominant product. The enzyme did not act on K-carrageenan. According to the criteria of Bergey's Manual of Systematic Bacteriology, the strain was assigned to the genus Vibrio.