Peptides removing in enzymatic membrane bioreactor Original Research Article

Applicability of thermolysin — one of proteolytic enzymes, in catalyzing the process of hydrolysis of a mixture of polypeptides being a waste product of dairy industry was discussed in the study. Process temperature (50°C) was selected and kinetics of the process involving a native enzyme was determined. The Michaelis–Menten equation constants are KM = 34.29 g L−1, k3 = 14,285.7 gpr. ⋅ genz.−1 h−1. In order to reuse the catalyst a possibility of its immobilization by adsorption on the surface of a cellulose nitrate membrane was investigated. Efficiency and stability of binding and activity of the adsorbed enzyme towards a mixture of polypeptides were determined. In the applied range of substrate the model of first-order kinetics can be applied and the value of the constant is kr = 6615.4 h−1. Due to low stability of the immobilized preparation results most probably from a gradual detachment of the enzyme from the membrane it was proposed to carry out the continuous process in an integrated system which would combine the advantages of an agitated reactor (high enzyme activity and stability) with those of a packed bed (high enzyme concentration in small volume, low substrate concentration at the exit). The presence of a properly selected membrane causes that enzyme molecules cannot leave the bioreactor, they can only transfer between the packed zone on the membrane surface and the zone of complete mixing in the reactor volume. So, the membrane will have two functions: a separator for the native enzyme and a matrix for enzyme immobilization and will be created dynamically.