At last, Endo-chitosanase ChA and exo-chitosanase ChB were isolated by IEC method. 2% (W/V) solution of chitosan degraded by ChA or ChB respectively was ultrafiltered by membrane with MWCo 2kDa.

• 经过内切酶ChA与外切酶ChB降解的2%25(W/V)壳聚糖溶液,用截留分子量为2kDa的膜进行超滤,得到分子量小于2kDa的滤过液,经真空浓缩、喷雾干燥,得到产品S_1和S_2。