Improving stability of a novel dextran-degrading enzyme from marine Arthrobacter oxydans KQ11

Dextranases can hydrolyze dextran, so they are used in the sugar industry to mitigate the milling problems associated with dextran contamination. Few studies have been carried out on the storage stability of dextranase, let alone the dextranase of Arthrobacter oxydans KQ11 isolated from sea mud samples. This study improved the storage stability of dextranase from marine A. oxydans KQ11 by adding enzymatic protective reagents (stabilizer and antiseptic). Initially, the conditions (55 °C and 30 min) for maintaining 50% dextranase activity were obtained. Then, the best stabilizers of dextranase were obtained, namely, glycerol (16%), sodium acetate (18%) and sodium citrate (20%). Results showed that p-hydroxybenzoic acid compound sodium acetate (0.05%), d-sodium isoascorbiate (0.03%), and potassium sorbate (0.05%) were the best antiseptics. Subsequent validation experiment showed that dextranase with enzymatic protective reagents maintained 70.8% and 28.96% activities at the 13th week at 25 and 37 °C, respectively.