Biocatalytically active silCoat-composites entrapping viable Escherichia coli

Advances in biological production of acetoin: a comprehensive overview

Acetoin, a high-value-added bio-based platform chemical, is widely used in foods, cosmetics, agriculture, and the chemical industry. It is an important precursor for the synthesis of: 2,3-butanediol, liquid hydrocarbon fuels and heterocyclic compounds. Since the fossil resources are becoming increasingly scarce, biological production of acetoin has received increasing attention as an alternative to chemical synthesis. Although there are excellent reviews on the: application, catabolism and fermentative production of acetoin, little attention has been paid to acetoin production via: electrode-assisted fermentation, whole-cell biocatalysis, and in vitro/cell-free biocatalysis. In this review, acetoin biosynthesis pathways and relevant key enzymes are firstly reviewed. In addition, various strategies for biological acetoin production are summarized including: cell-free biocatalysis, whole-cell biocatalysis, microbial fermentation, and electrode-assisted fermentation. The advantages and disadvantages of the different approaches are discussed and weighed, illustrating the increasing progress toward economical, green and efficient production of acetoin. Additionally, recent advances in acetoin extraction and recovery in downstream processing are also briefly reviewed. Moreover, the current issues and future prospects of diverse strategies for biological acetoin production are discussed, with the hope of realizing the promises of industrial acetoin biomanufacturing in the near future.

Ultralong-Discharge-Time Biobattery Based on Immobilized Enzymes in Bilayer Rolled-Up Enzymatic Nanomembranes

Glucose biofuel cells (GBFCs) are highly promising power sources for implantable biomedical and consumer electronics because they provide a high energy density and safety. However, it remains a great challenge to combine their high power density with reliable long-term stability. In this study, a novel GBFC design based on the enzyme biocatalysts glucose dehydrogenase, diaphorase, and bilirubin oxidase immobilized in rolled-up titanium nanomembranes is reported. The setup delivers a maximum areal power density of ≈3.7 mW cm^-2 and a stable power output of ≈0.8 mW cm^-2 . The power discharges over 452 h, which is considerably longer than reported previously. These results demonstrate that the GBFC design is in principle a feasible and effective approach to solve the long-term discharge challenge for implantable biomedical device applications.

Biocatalytic Valorization of Furans: Opportunities for Inherently Unstable Substrates

Biogenic furans (furfural and 5-hydroxymethylfurfural) are expected to become relevant building blocks based on their high degree of functionality and versatility. However, the inherent instability of furans poses considerable challenges for their synthetic modifications. Valorization routes of furans typically generate byproducts, impurities, wastes, and a cumbersome downstream processing, compromising their ecological footprint. Biocatalysis may become an alternative, given the high selectivity of enzymes, together with the mild reaction conditions applied. This Review critically discusses the options for enzymes in the upgrading of furans. Based on previous reports, a variety of biocatalytic transformations have been applied to furans, with successful cases both in aqueous and in water-free media. Options comprise the biodetoxification of toxic furans in hydrolysates, selective syntheses based on oxidation-reduction processes, solvent-free esterifications, or carboligations to afford C₁₂ derivatives. Reported strategies show in general promising but still modest productivities (2-30 g_product  L^-1  d^-1 , depending on the example). There are opportunities with high potential and deserving of further development, scale-up, and technoeconomic assessment, to entirely validate them as realistic alternatives.

Recent advances in whole cell biocatalysis techniques bridging from investigative to industrial scale

Recent advances in biocatalysis have strongly boosted its recognition as a valuable addition to traditional chemical synthesis routes. As for any catalytic process, catalyst's costs and stabilities are of highest relevance for the economic application in chemical manufacturing. Employing biocatalysts as whole cells circumvents the need of cell lysis and enzyme purification and hence strongly cuts on cost. At the same time, residual cell wall components can shield the entrapped enzyme from potentially harmful surroundings and aid to enable applications far from natural enzymatic environments. Further advantages are the close proximity of reactants and catalysts as well as the inherent presence of expensive cofactors. Here, we review and comment on benefits and recent advances in whole cell biocatalysis.