Role of hydrodynamic flow parameters in lipase deactivation in bubble column reactor

The dynamic environment within the bioreactor and in the purification equipment is known to affect the activity and yield of enzyme production. In the present work, the effect of hydrodynamic flow parameters (P-G/V, epsilon(max), (tau) over bar (S), tau(S,max), (tau) over bar (N) and tau(N,max)) and interfacial flow parameters ((epsilon) over bar (G), (a) under bar and k(L)(a) under bar) on the activity of lipase has been comprehensively investigated in bubble column reactors. Lipase solution was subjected to hydrodynamic flow parameters in 0.15 and 0.385 m i.d. bubble column reactors over a wide range of superficial gas velocity (0.01 < V-G < 0.4-ms(-1)). The flow parameters were estimated using an in-house CFD simulation code based on k-epsilon approach. The extent of lipase deactivation in both the columns was found to increase with an increase in hydrodynamic and interfacial flow parameters. However, at equal value of any of these parameters, the extent of deactivation was different in the two columns. The rate of deactivation was found to follow first order kinetics. An attempt has been made to develop rational correlations for the extent of deactivation as well as for the deactivation constant. The rate of deactivation was found to be depending on the average turbulent normal stress and interfacial flow parameters such as bubble diameter and bubble rise velocity. (c) 2005 Elsevier Ltd. All rights reserved.