In this issue

Abstract

AbstractExpression system for high‐throughput screening.Aerts et al., Eng. Life Sci. 2011, 11, 10–19.The bottleneck of directed evolution and optimization of biocatalytic enzymes is usually the screening of mutants in multiwell plates. Before a library can be screened, soluble expression of the enzymes has to be achieved. To reduce the amount of consumables and number of pipetting steps in high‐throughput screening, Wim Soetaert et al. developed a constitutive expression system comprising four constitutive promoters expressing the target protein at differing strengths. In this issue, they demonstrate the use of this expression system for expression of sucrose phosphorylase (SP) from a range of microorganisms in E. coli. They could show effective expression of all target proteins with different promoters and at varying temperatures. This new expression system will present an indispensable tool to optimize enzyme expression for small scale expression and high‐throughput screening……………10http://dx.doi.org/10.1002/elsc.201000065magnified imageMagnetic lysozyme separationEichholz et al., Eng. Life Sci. 2011, 11, 75–83.Magnetic separation is commonly used at lab‐scale. In order to apply the same concept at a larger scale or even for industrial separation processes, effective and economical procedures have to be provided. First, suitable process equipment has to be developed. Second, the magnetic particles have to be manufactured with a stable surface functionalization and long‐term stability for their reuse. In this issue, researchers from the Karlsruhe Institute of Technology (KIT), Germany, introduce a new magnetic filter that overcomes the capacity limitations of the current high‐gradient magnetic separation technology. Magnetic beads with a strong acid cation‐exchange surface functionalization are synthesized and the separation procedure is implemented in a single‐unit operation. They successfully demonstrate the working principle by selective recovery of lysozyme from hen egg white with a purification factor of PF=36 and a purity P=0.83.……………75http://dx.doi.org/10.1002/elsc.201000121magnified imageFermentation process supervisionGnoth et al., Eng. Life Sci. 2011, 11, 94–106.Highly reproducible fermentation processes are essential for the production of recombinant therapeutic proteins and demanded by regular authorities such as the FDA or EMEA. A major prerequisite for correct process control is that the measurement devices work correctly. Feedback control is the best way to keep the cultures on track. However, feedback controllers require accurate online values of the controlled variables. To assess whether the measurement signals are correct, process supervision techniques are required. In the case where a process failure has occurred and the incorrectly measured variables have been identified, automated fail‐safe techniques must be started. In this issue, colleagues from Halle, Germany, and Kaunas, Lithuania, compare different approaches of process supervision and fail‐safe routines in the same production process of a recombinant protein in E. coli. They assess different control mechanism and models and compare their advantages and disadvantages.……………94http://dx.doi.org/10.1002/elsc.201000114magnified image