Purification and characterization of a novel marine Arthrobacteroxydans KQ11 dextranase

• The enzyme gave a single band in SDS-PAGE and BD-SDS-PAGE.
• 10 mM Co2+ enhanced dextranase activity for 196%.
• The enzyme maintained more than 60% activity at 60 °C for 1 h.
• The purified fold and yield were higher than reported with similar process.
• The enzyme had obvious effect on S. mutans biofilm and mixed-species oral biofilm.

Dextranases can hydrolyze dextran deposits and have been used in the sugar industry. Microbial strains which produce dextranases for industrial use are chiefly molds, which present safety issues, and dextranase production from them is impractically long. Thus, marine bacteria to produce dextranases may overcome these problems. Crude dextranase was purified by a combination of ammonium sulfate fractionation and ion-exchange chromatography, and then the enzyme was characterized. The enzyme was 66.2 kDa with an optimal temperature of 50 °C and a pH of 7. The enzyme had greater than 60% activity at 60 °C for 1 h. Moreover, 10 mM Co2+ enhanced dextranase activity (196%), whereas Ni2+ and Fe3+ negatively affected activity. 0.02% xylitol and 1% alcohol enhanced activity (132.25% and 110.37%, respectively) whereas 0.05% SDS inhibited activity (14.07%). The thickness of S. mutans and mixed-species oral biofilm decreased from 54340 nm to 36670 nm and from 64260 nm to 43320 nm, respectively.