NUCLEATION AND GROWTH OF MICROBIAL LIPASE CRYSTALS FROM CLARIFIED CONCENTRATED FERMENTATION BROTHS

Bulk crystallization is emerging as a new industrial operation for pro tein recovery. Characterization of bulk protein crystallization is mor e complex than protein crystallization for structural study where sing le crystals are grown in flow cells. This is because both nucleation a nd crystal growth processes are taking place while the supersaturation falls. An algorithm is presented to characterize crystallization usin g the rates of the two kinetic processes, nucleation and growth. The v alues of these rates allow ready comparison of the crystallization pro cess under different operating conditions. The crystallization, via ad justment to the isoelectric pH of a fungal lipase from clarified ferme ntation broth, is described for a batch stirred reactor. A maximum nuc leation rate of five to six crystals formed per microliter of suspensi on per second and a high power dependency (approximate to 11) on the d egree of supersaturation were found. The suspended protein crystals we re found to grow at a rate of up to 15-20 nm/s and also to exhibit a h igh power dependency (approximate to 6) of growth rate on the degree o f supersaturation. (C) 1998 John Wiley & Sons, Inc.