Studies on isolation and purification of penicillin acylase by adsorption on bentonite

When bentonite I as an absorbent according to 0.6% (w/v) was added to the supernatant of the fermentation broth for adsorption of penicillin acylase from Bacillus megatherium, 100% activity of penicillin acylase and about 10% protein in the supernatant were adsorbed. The adsorption of enzyme was not obviously changed with different pH and salt concentration of the supernatant. Various kinds of buffer with different pH were used to wash the enzyme-adsorbent complex. Only 1% enzyme activity adsorbed was washed out; however, it can wash out about 15% protein adsorbed. When phosphate buffer containing 10% PEG and NaCl as an eluent was used to elute the complex, 100% of enzyme activity adsorbed on the complex would be eluted, and purification and concentration times of enzyme could achieve about 25 and 6, respectively. The isolation and purification process can be carried out at room temperature. Its characters were very simple and showed a high recovery yield of enzyme activity, and it can be directly used for isolation and purification of penicillin acylase from the fermentation broth.