Abstract:A strain of agarase-producing Vibrio sp. BY-7 was isolated from abalone farm samples collected in Lianjiang and Putian. The coding gene of agarase VsAgaBY-7 was amplified using the thermal asymmetric interlaced PCR （TAIL-PCR） technique. The agarase gene vsAgaBY-7， encoding the mature peptide， was cloned into the plasmid pET-22b（+） and heterologously expressed in Escherichia coli BL21 （DE3）. The recombinant agarase VsAgaBY-7 was purified by Ni-affinity chromatography， and its enzymatic properties were characterized. The results showed that the optimal pH and temperature of VsAgaBY-7 were 7.0 and 40 ℃， respectively.The enzyme remained stable within pH6.0-8.0 and below 40 ℃. VsAgaBY-7 was sensitive to most heavy metal ions， whereas Ca2+ and Mg2+ significantly promoted its activity. Kinetic analysis revealed that the Km， Vmax，and kcat values of VsAgaBY-7 toward agarose were 1.85 g/L， 31.54 U/mg， and 54.69 s-1， respectively. The hydrolysis product of agarose by VsAgaBY-7 was single， indicating that only yielding neoagarotetraose is a novel β-exo-agarase.