Cell-free biosynthesis of ω-hydroxy acids boosted by a synergistic combination of alcohol dehydrogenases

The activity orchestration of an unprecedented cell-free enzyme system with self-sufficient cofactor recycling enables the step-wise transformation of aliphatic diols into -hydroxy acids at the expense of molecular oxygen as electron acceptor. The efficiency of the biosynthetic route was maximized when two compatible alcohol dehydrogenases were selected as specialist biocatalysts for each one of the oxidative steps required for the oxidative lactonization of diols. The cell-free system reached up to 100% conversion using 100 mM of linear C5 diols, and performed the dessymetrization of prochiral branched diols into the corresponding -hydroxy acids with an exquisite enantioselectivity (ee > 99%). Green metrics demostrate a superior sustanability of this system compared to traditional metal catalysts and even to whole cells for the synthesis of 5-hydroxy petanoic acid. Finally, the cell-free system was assembled into a consortium of heterogeneous biocatalysts that allowed the enzyme reutilization. This cascade illustrates the potential of systems biocatalysis to access new heterofunctional molecules such as -hydroxy acids.

Ionic Liquids for Development of Heterogeneous Catalysts Based on Nanomaterials for Biocatalysis

The development of effective methods of enzyme stabilization is key for the evolution of biocatalytic processes. An interesting approach combines the stabilization process of proteins in ionic liquids and the immobilization of the active phase on the solid support. As a result, stable, active and heterogeneous biocatalysts are obtained. There are several benefits associated with heterogeneous processes, as easy separation of the biocatalyst from the reaction mixture and the possibility of recycling. Accordingly, this work focused on the supported ionic liquid phases as the efficient enzyme stabilization carriers, and their application in both continuous flow and batch biocatalytic processes.

Immobilization Screening and Characterization of an Alcohol Dehydrogenase and its Application to the Multi-Enzymatic Selective Oxidation of 1,-Omega-Diols

Alcohol dehydrogenase from Bacillus (Geobacillus) stearothermophilus (BsADH) is a NADH-dependent enzyme catalyzing the oxidation of alcohols, however its thermal and operational stabilities are too low for its long-term use under non-physiological conditions. Enzyme immobilizations emerges as an attractive tool to enhance the stability of this enzyme. In this work, we have screened a battery of porous carriers and immobilization chemistries to enhance the robustness of a His-tagged variant of BsADH. The selected carriers recovered close to 50% of the immobilized activity and increased enzyme stability from 3 to 9 times compared to the free enzyme. We found a trade-off between the half-life time and the specific activity as a function of the relative anisotropy values of the immobilized enzymes, suggesting that both properties are oppositely related to the enzyme mobility (rotational tumbling). The most thermally stable heterogeneous biocatalysts were coupled with a NADH oxidase/catalase pair co-immobilized on porous agarose beads to perform the batch oxidation of five different 1,ω-diols with in situ recycling of NAD+. Only when His-tagged BsADH was immobilized on porous glass functionalized with Fe3+, the heterogeneous biocatalyst oxidized 1, 5-pentanediol with a conversion higher than 50% after five batch cycles. This immobilized multi-enzyme system presented promising enzymatic productivities towards the oxidation of three different diols. Hence, this strategical study accompanied by a functional and structural characterization of the resulting immobilized enzymes, allowed us selecting an optimal heterogeneous biocatalyst and their integration into a fully heterogeneous multi-enzyme system.

Recombinant strains producing thermostable lipase from Thermomyces lanuginosus and their use in heterogeneous biocatalysis, including in the processes of low-temperature synthesis of esters

Abstract-This work was devoted to the construction of recombinant strains Escherichia coli BL21 (DE3) and Pichia pastoris X33, producing a 1,3-specific thermostable lipase from Thermomyces lanuginosus. The sequences of two lipase genes were optimized for expression in bacteria and methylotrophic yeasts, then synthesized and cloned into the corresponding expression vectors. As a result of genetic engineering manipulations, E. coli and P. pastoris strains were constructed that efficiently produced recombinant lipase from T. lanuginosus, which accumulated in the cytoplasm in an amount of 30-40% of the total cellular protein. Recombinant P. pastoris clones secreted lipase into the nutrient medium at a concentration of at least 1 g/L. Lipases produced by the recombinant clones, designated as rE.coli/lip and rPichia/lip, respectively, contained a six-histidine sequence (-His6) in the C-terminal region. The resulting lipases were immobilized on/in solid inorganic supports in order to develop heterogeneous biocatalysts (HB) for the enzymatic conversion of triglycerides and fatty acids. The rPichia/lip enzyme was adsorbed on mesoporous silica and macroporous carbon aerogel. The properties of the prepared HB, their enzymatic activity, substrate specificity and operational stability were studied in the reaction of esterification of fatty acids with aliphatic alcohols in organic solvents at 20 ± 2°C. It was found that immobilized lipases had a relatively wide substrate specificity, as well as high operational stability, and the prepared HB almost completely retained their high esterifying activity for several tens of reaction cycles. Key words: Escherichia coli, Pichia pastoris, recombinant strains-producers, Thermomyces lanuginosus lipase gene, immobilization, biocatalysts, esterification The authors are grateful to V. L. Kuznetsov for the provided samples of carbon aerogel and A. V. Ryabchenko for gene-engineering manipulation aimed at obtaining the recombinant rE. coli strain, a producer of the rE.coli/lip enzyme. The work was carried out under the Project on Fundamental Research within the framework of a state assignment to the Institute for Catalysis "Catalysts and Processes of Renewable Raw Material Conversion" (no. 0239-2021-0005).

BIOCATALYTIC PROCESSES OF LOW-TEMPERATURE SYNTHESIS OF ESTERS. MODULATION OF THE FUNCTIONAL PROPERTIES OF LIPASE BY THE CHOICE OF SOLVENT AND SUPPORT FOR IMMOBILIZATION

Biocatalytic processes for the synthesis of valuable products, such as different esters for various purposes, have been studied using heterogeneous biocatalysts prepared by immobilizing the recombinant lipase rPichia/lip on mesoporous silica (SiO2) and macroporous carbon aerogel (MCA). It was found that the functional properties of immobilized lipase, such as enzymatic activity, specificity toward pair of substrates (acid and alcohol), the molecules of which differ in the number of carbon atoms (C), as well as operational stability, depended on the method of adsorptive immobilization, the chemical nature of the support, and polarity of the organic solvent, i.e. logP. The functional properties of rPichia/lip have been shown to be modulated by the selection of an organic solvent and support for lipase immobilization.

Self-sufficient asymmetric reduction of β-ketoesters catalysed by a novel and robust thermophilic alcohol dehydrogenase co-immobilised with NADH

A highly robust and productive self-sufficient heterogeneous biocatalysts to asymmetrically reduce β-ketoesters.

Heterogeneous Biocatalysts for the Final Stages of Deep Processing of Renewable Resources into Valuable Products

Heterogeneous biocatalysis is a part of biotechnology and it has commercial potential for industrial implementation, in particular the final stages of deep processing of renewable raw materials. The commercially attractive heterogeneous biocatalysts are prepared by immobilizing practically valuable enzymatic active substances onto solid inorganic supports. Heterogeneous biocatalytic processes of the target conversion of substrate into valuable market product are carried out in periodic or continuous modes using traditional batch and packed-bed reactors, as well as novel types of vortex reactors in accordance with the principles of green chemistry. Heterogeneous biocatalysts for the final stages of deep processing of vegetable raw materials such as starch and oils are described here. One of the biocatalysts is glucoamylase immobilized by adsorption on mesoporous carbon support Sibunit™ type. This glucoamylase-active biocatalyst is used at the stage of starch saccharification, i.e., hydrolysis of dextrin to treacle and glucose syrups used in food and confectionary industries. The second of the biocatalysts is recombinant T. lanuginosus lipase immobilized on mesoporous silica KSK™ type and macroporous carbon aerogel. These lipase-active biocatalysts can effectively compete with traditional organic synthesis catalysts, and they are used in low-temperature processes carried out in unconventional anhydrous media such as interesterification of vegetable oils’ triglycerides with ethyl acetate for producing ethyl esters of fatty acids (biodiesel and vitamin F) and esterification of fatty acids with aliphatic alcohols for synthesis of various esters used as fragrances, flavorings, odors, emollients, and nonionic surfactants in perfume and cosmetics industries. The prepared heterogeneous biocatalysts due to their high enzymatic activity and operational stability are promising for practical implementation.