Continuous enzymatic penicillin G hydrolysis in countercurrent water-butyl acetate biphasic systems

Penicillin G (Pen G) was continuously hydrolyzed into phenylacetic acid (PAA) and aminopenicillanic acid (APA) by penicillin acylase in countercurrently contacted water-butyl acetate biphasic systems. A set of three mixer-settlers was used to establish countercurrent contact of the two immiscible liquid phases. The enzymatic reaction was catalyzed by immobilized penicillin acylase. Pen G was fed in the central mixer. APA continuously left the system with the aqueous exit stream and PAA with the organic exit stream. The conversion in the countercurrently contacted biphasic system was significantly higher than the conversion that can be achieved in an equivalent batch system. A mathematical model, which is based on partition and reaction equilibria, was used to predict the concentrations and pH along the countercurrent reactor. Provided that no APA crystallization occurs, the mathematical model predicted the conversion and the pH profile in the mixer-settler cascade accurately.