Construction of microbial cell factories for industrial bioprocesses

The development of industrial microbial processes is gaining unprecedented momentum. Increased concern for environmental issues and the prospect of declining petroleum resources has shifted the industrial focus increasingly to microorganisms as biocatalysts. At the same time systems biology and synthetic biology supply industry and academia with new tools to design optimal microbial cell factories. Among the tools are systems biology approaches allowing the modelling of cellular networks for rational strain design, single cell analyses methods for gaining insight into population hetereogeneity, and an exciting combination of tools from structural biology and synthetic biology, permitting the catalysis of new (unnatural) enzymatic reactions or the production of new (unnatural) chemicals. This perspective article outlines recent advances and new developments within the field of microbial cell factory design. Copyright © 2012 Society of Chemical Industry     

Zum Tragverhalten der selbstregulierenden interaktiven Membrangründung

On the load bearing behavior of the self‐regulating interactive membrane foundation system The paper reports on a new foundation system, the self‐regulating membrane foundation, for embankments on deep soft soil deposits, such as stockpiles or infrastructure embankments. The load bearing behavior of the system was analyzed by means of centrifuge model tests and comprehensive numerical simulations, such as global sensitivity analyses and parametric studies. The results of those analyses and the derived design approach are presented in the paper. The paper concludes with a validation of the design approach, by comparison with results of the numerical simulation.     

Problems in use of supported liquid-phase catalysts in fluidized bed reactors

Since SLP catalysts can become irreversibly deactivated due to evaporation of the solvent used to prepare the contacts, a saturation technique is proposed to stabilize the catalysts' activity. Application of this technique requires isothermal reaction conditions which can be achieved directly in fluidized bed reactors. Although the fluidization properties of SLP catalysts are mainly determined by interparticle forces, it can be shown that this type of reactor is suitable for an SLP-catalyzed gas reaction provided that a number of prerequisites are fulfilled. Taking a hydroformylation reaction catalyzed by an Rh complex dissolved in dimethyl glycol phthalate as an example, it is demonstrated that the activity of the prepared SLP catalyst can, indeed, be stabilized by saturation of the reactant gas mixture with the employed solvent.     

Differential mobility spectrometry of isomeric protonated dipeptides: modifier and field effects on ion mobility and stability

The ability to resolve isomeric protonated dipeptides was investigated with the new technique of differential ion mobility mass spectrometry that uses "modifier" molecules to enhance differential mobility. Two pairs of protonated peptides [glycine-alanine (GlyAla) and alanine-glycine (AlaGly), glycine-serine (GlySer) and serine-glycine (SerGly)] and eight different modifiers (water, 2-propanol, 1,5-hexadiene, 2-chloropropane, chlorobenzene, dichloromethane, acetonitrile, and cyclohexane) were used in the initial study. Separation of the protonated peptides was found to be dependent on the mass and proton affinity of the modifier and combinations of functionalities present in the modifier and the analyte ion. Six of the eight modifiers (water, 2-propanol, chlorobenzene, cyclohexane, dichloromethane, and acetonitrile) were able to separate the protonated isomeric peptide pairs, and generally, modifiers with electron-rich groups performed the best. In the presence of some modifiers, a reduction of ion current was observed under the highest field conditions (>115 Td). Dopant-catalyzed isomerization, likely by proton-transport catalysis, and field-induced fragmentation may have contributed to these losses. Two high vapor pressure modifiers, 1,5-hexadiene and 2-chloropropane, significantly influenced ion formation leading to the formation of stable cluster populations that could be observed in the mass spectrometer. Although not a major concern, both fragmentation and influence of modifier evaporation warrant further studies in order to fully understand and possibly eliminate them.