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According to literature reports, there are two methods for the separation and purification of Sa:

(1) Classical methods include ammonium sulfate precipitation, ion exchange chromatography, crystallization and other processes. As ammonium sulfate makes SA and endogenous protease in the culture medium be concentrated and precipitated together, the protease function is strengthened, and SA molecules are degraded as a result. The molecular weight of SA finally separated is about 60KD, and many SA as the core of commodities are obtained after further treatment.

(2) affinity chromatography, using 2- imido biotin agarose gel 4B affinity column, and its affinity with SA decreased with the decrease of pH. In the range of pH 10~ 11, both of them were tightly bound. When pH was reduced to 4, SA was dissociated. Because the activity of SA was not affected in the range of pH 4~ 11, the effect of separation and purification was good. SA can be separated directly from the culture medium by this method, so the steps of precipitation and concentration are omitted, so the effect of endogenous protease is weakened.