Improving Product Specificity of Whole-Cell Alkane Oxidation in Nonconventional Media: A Multivariate Analysis Approach.

Two-liquid-phase reaction media have long been used in bioconversions to supply or remove hydrophobic organic reaction substrates and products to reduce inhibitory and toxic effects on biocatalysts. In case of the terminal oxyfunctionalization of linear alkanes by the AlkBGT monooxygenase the excess alkane substrate is often used as a second phase to extract the alcohol, aldehyde, and acid products. However, the selection of other carrier phases or surfactants is complex due to a large number of parameters that are involved, such as biocompatibility, substrate bioavailability, and product extraction selectivity.

Customized microscale approach for optimizing two-phase bio-oxidations of alkanes with high reproducibility.

Background: Numerous challenges remain to achieve industrially competitive space-time yields for bio-oxidations. The ability to rapidly screen bioconversion reactions for characterization and optimization is of major importance in bioprocess development and biocatalyst selection; studies at conventional lab scale are time consuming and labor intensive with low experimental throughput. The direct ω-oxyfunctionalization of aliphatic alkanes in a regio- and chemoselective manner is efficiently catalyzed by monooxygenases such as the AlkBGT enzyme complex from Pseudomonas putida under mild conditions.

Scalable preparation of -biocatalysts by use of a fluidized-bed reactor.

-biocatalysts are immobilized enzyme preparations with an outstanding robustness against leaching and mechanical stress and therefore promising tools for technical synthesis. They consist of a composite material made from a solid enzyme carrier and silicone. In this study, a method has been found to enable provision of these catalysts in large scale.

The Power of Biocatalysis: A One-Pot Total Synthesis of Rhamnolipids from Butane as the Sole Carbon and Energy Source.

Microbially derived surfactants, so-called biosurfactants, have drawn much attention in recent years and are expected to replace current petrochemical surfactants, owing to their environmental and toxicological benefits. One strategy to support that goal is to reduce production costs by replacing relatively expensive sugars with cheaper raw materials, such as short-chain alkanes. Herein, we report the successful one-pot total synthesis of rhamnolipids, a class of biosurfactants with 12 stereocenters, from butane as sole carbon and energy source through the design of a tailored whole-cell biocatalyst.

Biocatalytically active silCoat-composites entrapping viable Escherichia coli.

Application of whole cells in industrial processes requires high catalytic activity, manageability, and viability under technical conditions, which can in principle be accomplished by appropriate immobilization. Here, we report the identification of carrier material allowing exceptionally efficient adsorptive binding of Escherichia coli whole cells hosting catalytically active carbonyl reductase from Candida parapsilosis (CPCR2). With the immobilizates, composite formation with both hydrophobic and hydrophilized silicone was achieved, yielding advanced silCoat-material and HYsilCoat-material, respectively.