Special Issue "Novel Enzyme and Whole-Cell Biocatalysis"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Metal Catalysis".

Deadline for manuscript submissions: 30 November 2018

Special Issue Editor

Guest Editor
Prof. Dr. Thomas Brück

Technische Universität München (TUM), Department of Chemistry, Head of Industrial Biocatalysis, Raum/Room: CH-27543, Lichtenberg Str. 4, D-85748 Garching bei München, Deutschland/Germany
Website | E-Mail
Phone: +49-89-289-13253
Interests: biocaqtalytic biomass conversion; biocatalytic valorization of biogenic building blocks

Special Issue Information

Dear Colleagues,

The role of catalysis in realizing a sustainable, bioeconomy climate change drives the development of sustainable processes in the chemical industry. In this respect, the utilization of biomass feedstocks is key in realizing a sustainable bioeconomy on a global scale. The conversion of complex biomass resources into value adding products is challenging due to the inherent chemical complexity of these feedstocks. To this end the role of biocatalysts (whole cells or enzymes) is currently the dominant approach to achieve efficient conversion with high selectivity in aqueous reaction media. However, the recent advent of novel solvent systems, such as ionic liquids, and advances in chemical catalyst design now open new conversion routes combining both bio- and chemical catalysis towards conversion and refining of complex biomass into target products. This Special Issue of Catalysts will focus on new catalytic cascades that preferentially combine both bio-catalytic and chemical steps to generate renewable products. Contributions that report on new catalysts or bioprocess engineering solutions particularly using novel solvent or product isolation procedures systems are welcome.

Prof. Dr. Thomas Brück
Guest Editor

Manuscript Submission Information

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Keywords

  • biomass conversion
  • catalyst design
  • catalytic cascades
  • chemical catalysts
  • biocatalysts
  • process engineering
  • downstream processing

Published Papers (4 papers)

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Research

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Open AccessArticle The Synthetic Potential of Fungal Feruloyl Esterases: A Correlation with Current Classification Systems and Predicted Structural Properties
Catalysts 2018, 8(6), 242; https://doi.org/10.3390/catal8060242
Received: 21 May 2018 / Revised: 31 May 2018 / Accepted: 1 June 2018 / Published: 7 June 2018
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Abstract
Twenty-eight fungal feruloyl esterases (FAEs) were evaluated for their synthetic abilities in a ternary system of n-hexane: t-butanol: 100 mM MOPS-NaOH pH 6.0 forming detergentless microemulsions. Five main derivatives were synthesized, namely prenyl ferulate, prenyl caffeate, butyl ferulate, glyceryl ferulate, and
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Twenty-eight fungal feruloyl esterases (FAEs) were evaluated for their synthetic abilities in a ternary system of n-hexane: t-butanol: 100 mM MOPS-NaOH pH 6.0 forming detergentless microemulsions. Five main derivatives were synthesized, namely prenyl ferulate, prenyl caffeate, butyl ferulate, glyceryl ferulate, and l-arabinose ferulate, offering, in general, higher yields when more hydrophilic alcohol substitutions were used. Acetyl xylan esterase-related FAEs belonging to phylogenetic subfamilies (SF) 5 and 6 showed increased synthetic yields among tested enzymes. In particular, it was shown that FAEs belonging to SF6 generally transesterified aliphatic alcohols more efficiently while SF5 members preferred bulkier l-arabinose. Predicted surface properties and structural characteristics were correlated with the synthetic potential of selected tannase-related, acetyl-xylan-related, and lipase-related FAEs (SF1-2, -6, -7 members) based on homology modeling and small molecular docking simulations. Full article
(This article belongs to the Special Issue Novel Enzyme and Whole-Cell Biocatalysis)
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Open AccessArticle Cross-Linked Enzyme Aggregates of Feruloyl Esterase Preparations from Thermothelomyces thermophila and Talaromyces wortmannii
Catalysts 2018, 8(5), 208; https://doi.org/10.3390/catal8050208
Received: 18 April 2018 / Revised: 10 May 2018 / Accepted: 10 May 2018 / Published: 15 May 2018
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Abstract
Cross-linked enzyme aggregates (CLEA®) technology is a well-established method in the current literature for the low-cost and effective immobilization of several enzymes. The main advantage of this particular method is the simplicity of the process, since it consists of only two
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Cross-linked enzyme aggregates (CLEA®) technology is a well-established method in the current literature for the low-cost and effective immobilization of several enzymes. The main advantage of this particular method is the simplicity of the process, since it consists of only two steps. However, CLEA immobilization must be carefully designed for each desired enzyme, since the optimum conditions for enzymes can vary significantly, according to their physicochemical properties. In the present study, an investigation of the optimum CLEA immobilization conditions was carried out for eight feruloyl esterase preparations. Feruloyl esterases are a very important enzyme group in the valorization of lignocellulosic biomass, since they act in a synergistic way with other enzymes for the breakdown of plant biomass. Specifically, we investigated the type and concentration of precipitant and the crosslinker concentration, for retaining optimal activity. FAE68 was found to be the most promising enzyme for CLEA immobilization, since in this case, the maximum retained activity, over 98%, was observed. Subsequently, we examined the operational stability and the stability in organic solvents for the obtained CLEA preparations, as well as their structure. Overall, our results support that the maximum activity retaining and the stability properties of the final CLEAs can vary greatly in different FAE preparations. Nevertheless, some of the examined FAEs show a significant potential for further applications in harsh industrial conditions. Full article
(This article belongs to the Special Issue Novel Enzyme and Whole-Cell Biocatalysis)
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Open AccessArticle Over-Expression of the Thermobifida fusca β-Glucosidase in a Yarrowia lipolytica Transformant to Degrade Soybean Isoflavones
Catalysts 2018, 8(1), 24; https://doi.org/10.3390/catal8010024
Received: 4 January 2018 / Revised: 12 January 2018 / Accepted: 12 January 2018 / Published: 14 January 2018
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Abstract
A gene (bgl) encoding a β-glucosidase in thermophilic actinomycete Thermobifida fusca NTU 22 was cloned into a Yarrowia lipolytica expression system. Heterologous expression resulted in extracellular β-glucosidase production with activity as high as 630 U/mL in a Hinton flask culture filtrate.
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A gene (bgl) encoding a β-glucosidase in thermophilic actinomycete Thermobifida fusca NTU 22 was cloned into a Yarrowia lipolytica expression system. Heterologous expression resulted in extracellular β-glucosidase production with activity as high as 630 U/mL in a Hinton flask culture filtrate. This recombinant β-glucosidase was purified 9.2-fold from crude culture filtrate by DEAE-Sepharose FF column chromatography as measured by its increase in specific activity. The overall yield of the purified enzyme was 47.5%. The molecular weight of the purified β-glucosidase estimated by SDS-PAGE was 45 kDa, which agreed with the predicted molecular weight based on the nucleotide sequence. About 15% enzyme activity loss was observed after the enzyme was heat-treated at 50 °C for 180 min. It was also found that the activity of the enzyme was inhibited by Hg2+, Cu2+, Ba2+, Ag+, p-chloromercuribenzene, and iodoacetate. The β-glucosidase from T. fusca had the most activity for daidzein-7-glucoside and genistein-7-glucoside among the tested flavonoid glycosides, but there was moderate or little activity for luteolin-7-glucoside, cyanidine-3-glucoside, and quercetin-3-glucoside. These properties are important for the soybean isoflavone applications of this β-glucosidase. Full article
(This article belongs to the Special Issue Novel Enzyme and Whole-Cell Biocatalysis)
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Review

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Open AccessReview Waste into Fuel—Catalyst and Process Development for MSW Valorisation
Catalysts 2018, 8(3), 113; https://doi.org/10.3390/catal8030113
Received: 28 December 2017 / Revised: 8 March 2018 / Accepted: 12 March 2018 / Published: 14 March 2018
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Abstract
The present review paper highlights recent progress in the processing of potential municipal solid waste (MSW) derived fuels. These wastes come from the sieved fraction ( < 40 mm), which, after sorting, can differ in biodegradable fraction content ranging from 5–60%. The
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The present review paper highlights recent progress in the processing of potential municipal solid waste (MSW) derived fuels. These wastes come from the sieved fraction ( < 40 mm), which, after sorting, can differ in biodegradable fraction content ranging from 5–60%. The fuels obtained from these wastes possess volumetric energy densities in the range of 15.6–26.8 MJL−1 and are composed mainly of methanol, ethanol, butanol, and carboxylic acids. Although these waste streams are a cheap and abundant source (and decrease the fraction going to landfills), syngas produced from MSW contains various impurities such as organic compounds, nitrogen oxides, sulfur, and chlorine components. These limit its use for advanced electricity generation especially for heat and power generation units based on high temperature fuel cells such as solid oxide fuel cells (SOFC) or molten carbonate fuel cells (MCFC). In this paper, we review recent research developments in the continuous MSW processing for syngas production specifically concentrating on dry reforming and the catalytic sorbent effects on effluent and process efficiency. A particular emphasis is placed on waste derived biofuels, which are currently a primary candidate for a sustainable biofuel of tomorrow, catalysts/catalytic sorbents with decreased amounts of noble metals, their long term activity, and poison resistance, and novel nano-sorbent materials. In this review, future prospects for waste to fuels or chemicals and the needed research to further process technologies are discussed. Full article
(This article belongs to the Special Issue Novel Enzyme and Whole-Cell Biocatalysis)
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