**4.3.1 Purification of salt-tolerant acid protease of** *B. subtilis* **JM-3 and** *B. megaterium*  **KLP-98**

As shown in Table 1 and 2, proteases produced by *B. subtilis* JM3 and *B. megaterium* KLP-98 were purified by a similar procedure. Proteases in the culture media were precipitated by ammonium sulfate. The precipitates were dissolved, dialyzed, and applied to a DEAE-Sephadex ion exchange column. Proteins were eluted with an increasing gradient of NaCl. Fractions containing greater than 50% of maximal peak activity were pooled, dialyzed and applied to a Sephadex G-75 gel filtration column, and eluted with sodium acetate buffer (pH 5.5). Proteases produced by *B. subtilis* JM3 and *B. megaterium* KLP-98 were purified by 35.56 folds with 5.33% of yield and 18.83 folds with 15.3% of yield, respectively.


Table 1. Purification of *Bacillus subtilis* JM-3 protease from anchovy sauce (W.J. Kim and S.M. Kim, 2005).


Table 2. Purification of *Bacillus megaterium* KLP-98 protease from fermented squid (Fu et al., 2008).
