Studies on the removal of Escherichia coli cell debris by aqueous two-phase polymer extraction

Biotransformation of 12-hydroxystearic acid to gamma-decalactone: Comparison of two separation systems

Biotransformation of natural products to the natural flavoring, gamma-decalactone (GDL), has attracted considerable attention. However, improving its yield is challenging due to its high feedback inhibition of yeast cells, which lowers the productivity of the biotransformation process. In this study, we compared two in situ separation processes established by adding either resin (HZ-816) or cyclopentasiloxane (DC345) to a biotransformation medium and investigated their efficiency and effect on yeast metabolism. Compared with a control, yields from the medium with HZ-816 and DC345 increased by 140% and 175%, respectively. However, after 84 h of biotransformation, the protein leakage in the medium with HZ-816 and DC345 was respectively 2.04 times and 1.43 times that of the control. Meanwhile, the mortality of yeast cells was 32.8% and 24.0% in the medium with HZ-816 and DC345, respectively, whereas that in the control was 20.1%. Our findings indicate that a cyclase is involved in the final step of the biotransformation. The activity of the yeast cyclase in the DC345 system was 3.33 times greater than that in the HZ-816 system. The DC345 system was superior to the HZ-816 resin system in this separation process because its yield was 30.8% greater and it had less cellular damage. Thus, we showed that the DC345 system has potential as a new separation system for the production of GDL by biotransformation.

RNA partitioning accompanied by adsorption: high-molecular-mass RNA adsorbed at the interface like a particle

In a potassium phosphate-poly(ethylene glycol) (PEG) system. RNA partitioning was accompanied by adsorption at the interface, depending on the molecular mass. Low-molecular-mass RNA showed the typical partition behavior of a soluble substance. Conversely, high-molecular-mass RNA was significantly adsorbed at the interface in the potassium phosphate-PEG1500 system. The adsorbed amount was proportional to the added amount, regardless of the phase volume ratio. The partitioning of high-molecular-mass RNA showed an amount-ratio-dependent distribution like that of a particle.

An overview of continuous protein purification processes

As the sphere of influence of recombinant technology moves away from the laboratory bench, towards product commercialization, development of manufacturing and large scale process technology is becoming a major challenge and determinant for commercial success. The challenge is particularly acute for protein purification process development where protein purification costs tend to dominate overall process economics. The primary objective for process scale purification is to minimize cost for a purified product which meets specifications. Continuous processes may be used to facilitate achievement of the overall objectives. This review critically examines the use of continuous processing for protein purification and recovery operations. The processes have been divided into three general areas: adsorptive and chromatographic, electrophoretic, and extractive. Consideration is given to the operational advantages and limitations of the reviewed processes.