In this issue: Biotechnology Journal 5/2009

In silico filtration scale‐up Francis and Haynes , Biotechnol. J. 2009, 5, 674–683 Controlled shear affinity filtration (CSAF) is an integrated bioprocess that positions a contoured rotor above a membrane affinity chromatography column to purify a secreted protein product directly from cell culture, e.g. monoclonal antibodies. However, for industrial application an effective method for scale‐up is needed. To achieve this Francis and Haynes from Vancouver (Canada) used computational fluid dynamics (CFD) simulations to determine fluid hydrodynamics and expected filter performance for CSAF units with increasing size. This resulted in an in silico design of a preparative CSAF device, which allows processing of 1000 L cell culture in two hours. In addition, the authors report a method for the parallelization of CSAF units that can be applied to volumes exceeding 1000 L. Substrate absorption in gas/solid biocatalysis Dimoulal , et al., Biotechnol. J. 2009, 5, 712–721 Gas/solid biocatalysis has various potential applications, including fine chemical synthesis and toxic pollutant degradation. To gain a deeper insight into the enzyme microenvironment of a gas/solid system, researchers from Aachen and Jülich (Germany) studied the adsorption of water and substrates to dry deposited alcohol dehydrogenase from Lactobacillus brevis . To monitor the system the well‐characterized conversion of acetophenone catalyzed by alcohol dehydrogenase was chosen. While acetophenone is adsorbed to the deposited enzyme preparation at a significant level, comparable to the amount of adsorbed water, 2‐propanol was not adsorbed at a detectable level. Reaction kinetics will to be studied in the future. Inclusion bodies resolved Dürauer , et al., Biotechnol. J. 2009, 5, 722–729 Recombinant proteins produced in Escherichia coli are often deposited in so‐called inclusion bodies (IBs). The purification of proteins in IBs requires several steps, including solubilization and refolding of non‐native proteins. Researchers from Vienna (Austria) report a new method for high‐throughput screening of solubilization conditions and evaluation of dissolution kinetics carried out in conventional 96‐well plates. This involves simple measurements of absorbance at 600 nm and 280 nm to determine turbidity and protein concentration. This new method will contribute to a faster development in the early stage of recombinant protein recovery from E. coli .