Harald Brüssow, Carlos Canchaya, Wolf-Dietrich Hardt

Microbiology and Molecular Biology Reviews • 2004

<jats:sec><jats:title>SUMMARY</jats:title><jats:p>Comparative genomics demonstrated that the chromosomes from bacteria and their viruses (bacteriophages) are coevolving. This process is most evident for bacterial pathogens where the majority contain prophages or phage remnants integrated into the bacterial DNA. Many prophages from bacterial pathogens encode virulence factors. Two situations can be distinguished:<jats:italic>Vibrio cholerae</jats:italic>, Shiga toxin-producing<jats:italic>Escherichia coli</jats:italic>,<jats:italic>Corynebacterium diphtheriae</jats:italic>, and<jats:italic>Clostridium botulinum</jats:italic>depend on a specific prophage-encoded toxin for causing a specific disease, whereas<jats:italic>Staphylococcus aureus</jats:italic>,<jats:italic>Streptococcus pyogenes</jats:italic>, and<jats:italic>Salmonella enterica</jats:italic>serovar Typhimurium harbor a multitude of prophages and each phage-encoded virulence or fitness factor makes an incremental contribution to the fitness of the lysogen. These prophages behave like “swarms” of related prophages. Prophage diversification seems to be fueled by the frequent transfer of phage material by recombination with superinfecting phages, resident prophages, or occasional acquisition of other mobile DNA elements or bacterial chromosomal genes. Prophages also contribute to the diversification of the bacterial genome architecture. In many cases, they actually represent a large fraction of the strain-specific DNA sequences. In addition, they can serve as anchoring points for genome inversions. The current review presents the available genomics and biological data on prophages from bacterial pathogens in an evolutionary framework.</jats:p></jats:sec>

Ronald Benner, Jan Lay, Elizabeth K&nees et al.

Limnology and Oceanography • 1988

<jats:p>Carbon conversion efficiencies were determined for the bacterial utilization of lignocellulosic detritus in waters from an estuarine and a freshwater wetland. Conversion efficiencies during bacterial growth on lignocellulose averaged ∼30% in both estuarine (salt marsh) and freshwater (Okefenokee Swamp) samples. Our estimates of bacterial growth efficiencies on refractory particulate detritus are twofold to threefold higher than previous estimates owing, in large part, to the higher biovolume‐to‐carbon conversion factor (0.22 g C cm<jats:sup>‒3</jats:sup>) used in the present study to convert bacterial biovolumes into units of carbon. Bacterial growth on lignocellulosic detritus was N limited in salt‐marsh water and P limited in Okefenokee water; carbon conversion efficiencies increased to 45% upon addition of ammonium and phosphate to salt‐marsh and Okefenokee incubations, respectively. These results indicate that bacterial biomass produced at the expense of lignocellulosic detritus is likely to be an important nutrient source to food webs in aquatic ecosystems with an abundance of macrophyte detritus and favorable conditions for microbial decomposition.</jats:p>

Thomas Maskow, Dayo Olomolaiye, Uta Breuer et al.

Biotechnology and Bioengineering • 2004

<jats:title>Abstract</jats:title><jats:p>The microbial conversion of toxic substrates into valuable products in continuous culture requires the equivalent of a tight rope walk between formation of the desired product and intoxication of the microbial catalyst. The condition of the latter is reflected immediately by changes in heat flow rate and β‐dispersion in an electrical RF field. Therefore, these were applied to the example of the continuous growth‐associated synthesis of polyhydroxyalcanoates (PHA) from phenol by the bacterial strain <jats:italic>Variovorax paradoxus</jats:italic> DSM 4065. By controlling the supply of phenol to the chemostat, the rates of degradation, biomass formation, and synthesis of target product, respectively, were increasingly elevated until the onset of poisoning the organisms. The boundary between the maximum rates and the initiation of intoxication coincided with a sudden change in the heat flux. Using this occurrence, it was possible to develop a control strategy and test it successfully for a time period of 80 h. After 40 h the process stabilized at mean values, i.e., at rates of 92% phenol degradation, 100% biomass formation, and 70 – 75% of PHA formation compared with the situation shortly before poisoning the organisms. Using a moving‐average technique to filter the raw dielectric spectroscope data, changes were followed in biomass concentration of approximately 100 mg/L. However, this technique was not sensitive or rapid enough to control the process. © 2004 Wiley Periodicals, Inc.</jats:p>

Michael Funaro, Venkata Krishnamurthy Nemani, Zhihang Chen et al.

Cancer Research • 2012

<jats:title>Abstract</jats:title> <jats:p>Introduction Enzymes of non-human origin possess tremendous potential as anticancer agents, especially in enzyme-prodrug therapy. Unfortunately, these enzymes are recognized as foreign agents by the human immune system and are targeted by an immune response. This immune reaction limits enzymes’ efficacy, particularly in treatments requiring repeated dosing. Current strategies for deimmunizing these therapeutic enzymes are labor/time intensive and yield limited success. Encapsulating enzymes in a hydrogel, such as sodium alginate, can confer immunoprotection and enhance in vivo stability. Alginate serves as a barrier between enzyme and host and its porosity can be controlled to prevent antibody infiltration while allowing the diffusion of the prodrug and the drug. The bacterial enzyme cytosine deaminase (bCD) mediates the conversion of 5-fluorocytosine (5-FC) to the anticancer drug 5-fluorouracil (5-FU). We encapsulated the bCD in sodium alginate microbeads and tested enzyme efficacy post encapsulation as determined by conversion of 5-FC to 5-FU, with concomitant cell kill assays. Methods bCD was encapsulated in sodium alginate microbeads, ∼200 microns, using a NISCO microencapsulation system (www.nisco.ch). The beads were incubated with 5-FC (25, 50, 100 and 200 microM), and conversion to 5-FU was monitored over time using spectrophotometry. Unencapsulated bCD was used as controls. Then, microbeads were incubated with 9L rat glioma cells in the presence of 5-FC. Cytotoxicity of the enzyme-prodrug system to 9L cells was evaluated using an MTT assay. 5-FC alone in the absence of bCD and 5-FU were used as controls. Experiments were repeated using beads stored for 72 h at 4°C and 37°C and temperature effects on the stability of encapsulated bCD were noted. Results summary We observed the complete conversion of 5-FC to 5-FU for all concentrations of encapsulated enzyme, albeit at a slower rate than unencapsulated controls. Cytotoxicity of the encapsulated enzyme-prodrug system toward 9L cells was similar to that of 5-FU alone, and of unencapsulated controls, indicating that encapsulation had no deleterious effect on enzyme efficacy. Though the enzyme kinetics were slower for the stored beads (at 4°C and 37°C), these beads resulted in similar cell kill. Our results suggest that sodium alginate microencapsulation of bCD maintained the enzyme's functionality and may therefore be a suitable platform for immunoisolative enzyme-prodrug therapy. We are extending our work to other cancer cell lines and to in vivo study of the anti-tumor effects of these encapsulated enzymes. This system has the advantage of localized 5-FC to 5-FU conversion, thereby potentially reducing systemic toxicity and increasing the locally available dose of the toxic drug. The strategy can be extended to the encapsulation of enzyme-producing cells that serve as de novo drug factories.</jats:p> <jats:p>Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5632. doi:1538-7445.AM2012-5632</jats:p>

J. D. Robinson, K. H. Mann, J. A. Novitsky

Limnology and Oceanography • 1982

<jats:p>The efficiency with which particulate organic carbon from seaweed detritus was transformed to bacterial carbon was determined in the laboratory by comparing changes in bacterial numbers with changes in the organic carbon content of detritus in incubation experiments lasting between 2 and 36 days. In general, the efficiencies were highest (43%) in the shortest incubations and declined with increasing length of experiment to a mean of 22% at 36 days. Nitrogen enrichment of the cultures accelerated decomposition and increased bacterial abundance but did not lead to higher conversion efficiencies than those observed without enrichment. Of the initial detrital carbon, 54% was rapidly leached into the seawater and a further 23% was removed by microbial activity. The remaining material was relatively refractory and had a low C:N ratio. The results indicate that the C:N ratio of detritus is not a good indication of its nutritional value.</jats:p>

Wolfgang Zinth, Josef Wachtveitl

ChemPhysChem • 2005

<jats:title>Abstract</jats:title><jats:p><jats:italic>In this Minireview, we describe the function of the bacterial reaction centre (RC) as the central photosynthetic energy‐conversion unit by ultrafast spectroscopy combined with structural analysis, site‐directed mutagenesis, pigment exchange and theoretical modelling. We show that primary energy conversion is a stepwise process in which an electron is transferred via neighbouring chromophores of the RC. A well‐defined chromophore arrangement in a rigid protein matrix, combined with optimised energetics of the different electron carriers, allows a highly efficient charge‐separation process. The individual molecular reactions at room temperature are well described by conventional electron‐transfer theory.</jats:italic></jats:p>

Huan Wang, Xiaodong Peng, Hu Li et al.

Frontiers in Chemistry • 0

<jats:p>The complexity and recalcitrance of the lignin structure is a major barrier to its efficient utilization and commercial production of high-value products. In recent years, the “bio-funneling” transformation ability of microorganisms has provided a significant opportunity for lignin conversion and integrated biorefinery. Based on the chemical structure of lignin, this mini-review introduces the recent advances of lignin depolymerization by bacterial strains and the application of microbial lignin degradation in lipids production. Furthermore, the current challenges, future trends and perspectives for microbe-based lignin conversion to lipids are discussed.</jats:p>

A. Schug, S. M. Schoberth, H. Sahm

Acta Biotechnologica • 1987

<jats:title>Abstract</jats:title><jats:p>The conversion of lactose — the main constituent of whey — to methane and carbon dioxide was studied using different defined constructed cultures, imploying strains of <jats:italic>Methanosarcina barkeri, Methanobacterium bryantii, Escherichia coli, Acetobacterium woodii, Lactobacillus casei</jats:italic>, and <jats:italic>Lactobacillus plantarum</jats:italic>. The following combinations of strains (food chains) were studied with respect to efficiency and yield of lactose conversion (methane yield in parentheses): <jats:italic>E. coli</jats:italic> and <jats:italic>M. barkeri</jats:italic> (4.5–7.6%), <jats:italic>E. coli</jats:italic> and <jats:italic>M. bryantii</jats:italic> (13.3%),<jats:italic>E. coli, M. barkeri</jats:italic> and <jats:italic>M. bryantii</jats:italic> (54%), <jats:italic>L. casei, A. woodii</jats:italic> and <jats:italic>M. barkeri</jats:italic> (93.3%). These conversions were carried out in pH controlled batch fermentations. A very efficient coculture was a combination of <jats:italic>L. plantarum</jats:italic> with <jats:italic>A. woodii</jats:italic> and <jats:italic>M. barkeri</jats:italic>: in chemostat cultures lactose was converted to methane and carbon dioxide with a yield of about 90%, at dilution rates of 0.27 d<jats:sup>‐1</jats:sup>to 0.37 d<jats:sup>‐1</jats:sup>.</jats:p>

Izabella Ślęzak-Prochazka, Kornelia M. Batko, Andrzej Ślęzak

Entropy • 0

<jats:p>We evaluated the transport properties of a bacterial cellulose (BC) membrane for aqueous ethanol solutions. Using the Rr version of the Kedem–Katchalsky–Peusner formalism (KKP) for the concentration polarization (CP) conditions of solutions, the osmotic and diffusion fluxes as well as the membrane transport parameters were determined, such as the hydraulic permeability (Lp), reflection (σ), and solute permeability (ω). We used these parameters and the Peusner (Rijr) coefficients resulting from the KKP equations to assess the transport properties of the membrane based on the calculated dependence of the concentration coefficients: the resistance, coupling, and energy conversion efficiency for aqueous ethanol solutions. The transport properties of the membrane depended on the hydrodynamic conditions of the osmotic diffusion transport. The resistance coefficients R11r, R22r, and Rdetr were positive and higher, and the R12r coefficient was negative and lower under CP conditions (higher in convective than nonconvective states). The energy conversion was evaluated and fluxes were calculated for the U-, F-, and S-energy. It was found that the energy conversion was greater and the S-energy and F-energy were lower under CP conditions. The convection effect was negative, which means that convection movements were directed vertically upwards. Understanding the membrane transport properties and mechanisms could help to develop and improve the membrane technologies and techniques used in medicine and in water and wastewater treatment processes.</jats:p>

Yixin Zhang, Musen Wang, Samaila Usman et al.

Microbial Biotechnology • 2023

<jats:title>Abstract</jats:title><jats:p>To explore the biofuel production potential of <jats:italic>Caragana korshinskii</jats:italic> Kom., <jats:italic>Pediococcus acidilactici</jats:italic> and an exogenous fibrolytic enzyme were employed to investigate the fermentation profile, structural carbohydrates degradation, enzymatic saccharification and the dynamics of bacterial community of <jats:italic>C</jats:italic>. <jats:italic>korshinskii</jats:italic> silage. After 60 d of ensiling, all additives increased the fermentation quality. The highest lactic and acetic acids and lowest non‐protein nitrogen (NPN) and ammonia nitrogen (NH<jats:sub>3</jats:sub>‐N) were observed in <jats:italic>P. acidilactici</jats:italic> and <jats:italic>Acremonium</jats:italic> cellulase (PA + AC) treated silage. Additionally, all additives significantly increased the ferulic acid content and fibre degradability with the highest values obtained from PA + AC silage. The bacterial community in all silages was dominated by <jats:italic>P. acidilactici</jats:italic> throughout the entire fermentation process. The bacterial community was also modified by the silage additives exhibiting a relatively simple network of bacterial interaction characterized by a lower bacterial diversity in <jats:italic>P. acidilactici</jats:italic> (PA) treated silage. The highest 6‐phospho‐beta‐glucosidase abundance was observed in PA‐treated silage at the mid‐later stage of ensiling. PA treatment exhibited lower structural carbohydrates degradation but performed better in lignocellulose conversion during enzymatic saccharification. These results indicated that pretreating <jats:italic>C. korshinskii</jats:italic> improved its silage quality and potential use as a lignocellulosic feedstock for the production of bio‐product and biofuel.</jats:p>

Rajani Pydipalli

Asian Journal of Applied Science and Engineering • 0

<jats:p>To improve efficiency and scalability, this study investigates the integration of artificial intelligence (AI) and IT-enabled techniques for the microbial conversion of rubber waste in metabolic engineering. The primary goals are to build synthetic biology constructs for enhanced rubber degradation, optimize bioprocess parameters through IT techniques, and use computational tools for route optimization. Methodologically, the study synthesizes insights from AI-driven techniques and IT-enabled procedures through an extensive analysis of existing literature and secondary data sources. Notable discoveries underscore the progress made in synthetic biology design, bioprocess optimization, and pathway prediction, highlighting the transformative potential of AI-driven metabolic engineering for sustainably produced rubber. The consequences of the policy include the need for more funding for research infrastructure, capacity building, and regulatory monitoring to enable the ethical use and responsible deployment of AI technologies in biotechnology and to remove any technological implementation impediments. This work advances sustainable approaches to resource recovery and waste management for rubber, tackles global environmental issues, and advances the circular economy goal.</jats:p>

Giannis Penloglou, Alexandros Pavlou, Costas Kiparissides

Fermentation • 0

<jats:p>The intended circular economy for plastics envisages that they will be partially replaced by bio-based polymers in the future. In this work, the natural polyester polyhydroxybutyrate (PHB) was produced by Azohydromonas lata using cheese whey (CW) as a low-cost substrate. Initially, CW was evaluated as the sole carbon source for PHB production; it was found to be efficient and comparable to PHB production with pure sugars, such as saccharose or glucose, even when mild (with dilute acid) hydrolysis of cheese whey was performed instead of enzymatic hydrolysis. An additional series of experiments was statistically designed using the Taguchi method, and a dual optimization approach was applied to maximize the intracellular biopolymer content (%PHB, selected as a quantitative key performance indicator, KPI) and the weight average molecular weight of PHB (Mw, set as a qualitative KPI). Two different sets of conditions for the values of the selected bioprocess parameters were identified: (1) a carbon-to-nitrogen ratio (C/N) of 10 w/w, a carbon-to-phosphorous ratio (C/P) of 1.9 w/w, a dissolved oxygen concentration (DO) of 20%, and a residence time in the stationary phase (RT) of 1 h, resulting in the maximum %PHB (61.66% w/w), and (2) a C/N of 13.3 w/w, a C/P of 5 w/w, a DO of 20%, and a RT of 1 h, leading to the maximum Mw (900 kDa). A final sensitivity analysis confirmed that DO was the most significant parameter for %PHB, whereas C/N was the most important parameter for Mw.</jats:p>

John Phillips, Raymond Huhnke, Hasan Atiyeh

Fermentation • 0

<jats:p>Biomass and other carbonaceous materials can be gasified to produce syngas with high concentrations of CO and H2. Feedstock materials include wood, dedicated energy crops, grain wastes, manufacturing or municipal wastes, natural gas, petroleum and chemical wastes, lignin, coal and tires. Syngas fermentation converts CO and H2 to alcohols and organic acids and uses concepts applicable in fermentation of gas phase substrates. The growth of chemoautotrophic microbes produces a wide range of chemicals from the enzyme platform of native organisms. In this review paper, the Wood–Ljungdahl biochemical pathway used by chemoautotrophs is described including balanced reactions, reaction sites physically located within the cell and cell mechanisms for energy conservation that govern production. Important concepts discussed include gas solubility, mass transfer, thermodynamics of enzyme-catalyzed reactions, electrochemistry and cellular electron carriers and fermentation kinetics. Potential applications of these concepts include acid and alcohol production, hydrogen generation and conversion of methane to liquids or hydrogen.</jats:p>

Andrea C Humphries, David W Penfold, Lynne E Macaskie

Journal of Chemical Technology &amp; Biotechnology • 2007

<jats:title>Abstract</jats:title><jats:p>Use of biologically‐produced hydrogen (bio‐H<jats:sub>2</jats:sub>) as an electron donor for Cr(VI) reduction by native and palladized cells of <jats:italic>Desulfovibrio vulgaris</jats:italic> NCIMB 8303 was demonstrated. The bio‐H<jats:sub>2</jats:sub> was produced fermentatively by <jats:italic>Escherichia coli</jats:italic> HD701 (a strain upregulated with respect to formate hydrogenlyase expression) using glucose solution or two industrial confectionery wastes as fermentable substrates. Maximum Cr(VI) reduction occurred at the expense of bio‐H<jats:sub>2</jats:sub> using palladized biomass (bio‐Pd(0)), with negligible residual Cr(VI) remaining from a 0.5 mmol dm<jats:sup>−3</jats:sup> solution after 2.5 h. Use of bio‐H<jats:sub>2</jats:sub> as the electron donor for Cr(VI) reduction by agar‐immobilized bio‐Pd(0) in a continuous‐flow system gave 90% reduction efficiency at a flow residence time of 0.7 h, which was maintained for the duration of bio‐H<jats:sub>2</jats:sub> evolution by <jats:italic>E. coli</jats:italic> HD701. This study shows the potential to remediate toxic metal waste at the expense of food processing waste, as a sustainable alternative to landfilling. Copyright © 2007 Society of Chemical Industry</jats:p>

Amandeep Kaur, Anju Goyal, Sapna Kumari et al.

BIO Web of Conferences • 2024

<jats:p>This tutorial review summarizes the basic new concepts of green chemistry in relation to education and pharmaceutical industries. The origin and history of Green analytical chemistry is described in detail. Basic twelve principles are well summarized with suitable examples of each principle such as oxidation of alcohol, enzymatic reactions, and non-covalent derivatization. This article also covers the concept of E-factor for waste minimization, detailed various solvent selection guidelines and tools for betterment of synthetic pathways at laboratory and industrial level. The efficiency of green chemistry in organic synthesis for greenness of traditional organic synthesis methods are discussed. Nowadays, there is a constant need to add catalysts for chemical synthesis to minimize or downsize the risks correspondent with chemical manufacture. Catalyst helps to enhance air quality by reducing harmful gas emissions such as NOx. It cuts down on the use of VOCs (volatile organic compounds). It developed an alternative catalytic method which substitutes the usage of chlorine-based intermediates in chemical synthesis and processes. Biocatalysts is a term used to describe compounds that aid in the stimulation of biological reactions. In the fine chemical industry, cleaner biocatalytic alternatives are replacing traditional chemical operations.</jats:p>

Khaled F. Alshammari

Luminescence • 2024

<jats:title>Abstract</jats:title><jats:p>The efficient degradation of organic pollutants in diverse environmental matrices can be achieved through the synergistic application of piezo‐catalysis and photocatalysis. The focus of this study is on understanding the fundamental principles and mechanisms that govern the collaborative action of piezoelectric and photocatalytic materials. Piezoelectric nanomaterials, under mechanical stress, generate piezo‐potential, which, when coupled with photocatalysts, enhances the generation and separation of charge carriers. The resulting cascade of redox reactions promotes the degradation of a wide spectrum of organic pollutants. The comprehensive investigation involves a variety of experimental techniques, including advanced spectroscopy and microscopy, to elucidate the intricate interplay between mechanical and photoinduced processes. The influence of key parameters, such as material composition, morphology, and external stimuli on the catalytic performance, is systematically explored. This study contributes to the increasing knowledge of environmental remediation and lays the foundation for the development of advanced technologies using piezo and photocatalysis for sustainable pollutant removal.</jats:p>

Duygu Zabitler, Esra Ülker, Kübra Turan et al.

Topics in Catalysis • 0

<jats:title>Abstract</jats:title> <jats:p>Electrochemical sensors and biosensors have attracted considerable interest due to their wide range of applications in pharmaceutical analysis, drug detection, cancer diagnosis, and monitoring toxic elements in drinking water. These sensors are characterized by their affordability, ease of manufacturing, fast response times, compact size, and ability to detect multiple analytes simultaneously. Electrochemical sensors are promising tools as they can be designed to detect a variety of analytes. Common materials employed in sensor fabrication include conducting polymers, nanomaterials, and bioreceptors. This review provides a comprehensive summary of electrochemical sensors developed for the determination of various analytes in biological samples, such as blood, plasma, serum, cerebrospinal fluid, saliva, tears, sweat, and urine. It also discusses future considerations regarding recent critical studies aimed at advancing research toward the development of novel functional electrochemical biosensors for electrochemical detection in biological samples.</jats:p>

S. C. Barton

Handbook of Fuel Cells • 0

<jats:title>Abstract</jats:title> <jats:p>Biocatalysts represent a compelling alternative to precious metals as catalysts for low‐temperature fuel cell power systems. Enzymatic catalysts capable of reducing oxygen or oxidizing small organic molecules can be less expensive and manufacturable, and have favorable reaction selectivity as compared to precious metals. The key barriers to realization of practical biocatalyzed fuel cells are the insufficient current, power, and lifetime achievable with current devices. Recently, significant progress has been made in addressing these issues, from the standpoint of fundamental studies of electron transfer to enzymes, mediation of enzyme‐catalyzed reactions, and immobilization of enzymes in materials that confer stability and high surface area for heterogeneous reactions. In this article, we introduce concepts in enzyme catalysis for energy applications and describe important recent progress.</jats:p>

Xiqing Cheng, Shuai Zhang, Huihui Liu et al.

ACS Applied Materials &amp; Interfaces • 2020

Encapsulating nanopartiles/biomolecules into metal-organic freamworks (MOFs) has proven highly effective in creating new functions during their applications. However, it is highly desirable yet remains challenging to achieve the synergy of specific functions between MOF host and guest species. Herein, inspired by natural multienzyme system, a novel MOF composite biomimetic structure based on co-encapsulation of glucose oxidase (GOx) and L-arginine (L-Arg) into Cu-MOFs (CuBDC) with Fenton-like catalytic activity is designed for achieving synergistic antibacterial effect. Once activated by GOx-catalyzed glucose oxidation, a large amount of oxygen radicals, toxic ONOO- and NO are rapidly produced over this well-designed L-Arg/GOx@CuBDC through a double-cascade reaction. Thanking to the synergy of highly reactive species, outstanding antibacterial effects (bacterial inactivation ≥97%) are observed at very low doses (38 μg mL-1 for E. coli and 3.8 μg mL-1 for S. aureus). In addition, the in vivo experiment in mice demonstrated that the as-prepared L-Arg/GOx@CuBDC has good biocompatibility, indicating its good potential in practical applications. Such biomimetic multienzyme system proposes a new design idea for highly efficient antibiosis as well as even therapy of tumors.

M. Saini, Amuliya Kashyap, Shruti Bindal et al.

Frontiers in Microbiology • 2021

Gamma-glutamyl transpeptidase (GGT) enzyme is ubiquitously present in all life forms and plays a variety of roles in diverse organisms. Higher eukaryotes mainly utilize GGT for glutathione degradation, and mammalian GGTs have implications in many physiological disorders also. GGTs from unicellular prokaryotes serve different physiological functions in Gram-positive and Gram-negative bacteria. In the present review, the physiological significance of bacterial GGTs has been discussed categorizing GGTs from Gram-negative bacteria like Escherichia coli as glutathione degraders and from pathogenic species like Helicobacter pylori as virulence factors. Gram-positive bacilli, however, are considered separately as poly-γ-glutamic acid (PGA) degraders. The structure–function relationship of the GGT is also discussed mainly focusing on the crystallization of bacterial GGTs along with functional characterization of conserved regions by site-directed mutagenesis that unravels molecular aspects of autoprocessing and catalysis. Only a few crystal structures have been deciphered so far. Further, different reports on heterologous expression of bacterial GGTs in E. coli and Bacillus subtilis as hosts have been presented in a table pointing toward the lack of fermentation studies for large-scale production. Physicochemical properties of bacterial GGTs have also been described, followed by a detailed discussion on various applications of bacterial GGTs in different biotechnological sectors. This review emphasizes the potential of bacterial GGTs as an industrial biocatalyst relevant to the current switch toward green chemistry.

J. Chan, Jacqueline N. Watson, April Lu et al.

Biochemistry • 2012

Mutagenesis of the conserved glutamic acid of influenza type A (E277) and Micromonospora viridifaciens (E260) sialidases was performed to probe the contribution of this strictly conserved residue to catalysis. Kinetic studies of the E260D and E260C M. viridifaciens mutant enzymes reveal that the overall mechanism of action has not changed. That is, the mutants are retaining sialidases in which glycosylation and deglycosylation are rate-limiting for k(cat)/K(m) and k(cat), respectively. The solvent kinetic isotope effect and proton inventory on k(cat) for the E260C mutant sialidase provide strong evidence that the newly installed cysteine residue provides little catalytic acceleration. The results are consistent with the conserved aspartic acid residue (D92) becoming the key general acid/base residue in the catalytic cycle. In addition, the E277D mutant influenza type A sialidase is catalytically active toward 4-nitrophenyl α-D-sialoside, although no measurable hydrolysis of natural substrates was observed. Thus, mutating the glutamate residue (E277) to an aspartate increases the activation free energy of hydrolysis for natural substrates by >22 kJ/mol.

N. J. Reiter, Amy K. Osterman, A. Mondragón

Nucleic Acids Research • 2012

RNase P is an RNA-based enzyme primarily responsible for 5′-end pre-tRNA processing. A structure of the bacterial RNase P holoenzyme in complex with tRNAPhe revealed the structural basis for substrate recognition, identified the active site location, and showed how the protein component increases functionality. The active site includes at least two metal ions, a universal uridine (U52), and P RNA backbone moieties, but it is unclear whether an adjacent, bacterially conserved protein loop (residues 52–57) participates in catalysis. Here, mutagenesis combined with single-turnover reaction kinetics demonstrate that point mutations in this loop have either no or modest effects on catalytic efficiency. Similarly, amino acid changes in the ‘RNR’ region, which represent the most conserved region of bacterial RNase P proteins, exhibit negligible changes in catalytic efficiency. However, U52 and two bacterially conserved protein residues (F17 and R89) are essential for efficient Thermotoga maritima RNase P activity. The U52 nucleotide binds a metal ion at the active site, whereas F17 and R89 are positioned >20 Å from the cleavage site, probably making contacts with N−4 and N−5 nucleotides of the pre-tRNA 5′-leader. This suggests a synergistic coupling between transition state formation and substrate positioning via interactions with the leader.

Feili Lai, Wei Zong, Guanjie He et al.

Angewandte Chemie International Edition • 2020

Vacancy engineering has been proved repeatedly as an adoptable strategy to boost electrocatalysis, while its poor selectivity restricts the usage in nitrogen reduction reaction (NRR) as overwhelming competition from hydrogen evolution reaction (HER). Revealed by density functional theory calculations, the selenium vacancy in ReSe 2 crystal can enhance its electroactivity for both NRR and HER by shifting the d -band from -2.91 to -2.33 eV. To restrict the HER, we report a novel method by burying selenium vacancy-rich ReSe 2 @carbonized bacterial cellulose (V r -ReSe 2 @CBC) nanofibers between two CBC layers, leading to boosted Faradaic efficiency of 42.5% and ammonia yield of 28.3 μg h -1 cm -2 at a potential of -0.25 V at an abrupt interface. As demonstrated by the nitrogen bubble adhesive force, superhydrophilic measurements, and COMSOL Multiphysics simulations, the hydrophobic and porous CBC layers can keep the internal V r -ReSe 2 @CBC nanofibers away from water coverage, leaving more unoccupied active sites for the N 2 reduction (especially for the potential determining step of proton-electron coupling and transferring processes as *HNNH 2 → *H 2 NNH 2 ).

Xinyu Gao, Yihong Liu, Yuqing Li et al.

ACS Applied Materials &amp; Interfaces • 2023

Catalytic nanomedicine can in situ catalytically generate bactericidal species under external stimuli to defend against bacterial infections. However, bacterial biofilms seriously impede the catalytic efficacy of traditional nanocatalysts. In this work, MoSe2 nanoflowers (NFs) as piezoelectric nanozymes were constructed for dual-driven catalytic eradication of multi-drug-resistant bacterial biofilms. In the biofilm microenvironment, the piezoelectricity of MoSe2 NFs was cascaded with their enzyme-mimic activity, including glutathione oxidase-mimic and peroxidase-mimic activity. As a result, the oxidative stress in the biofilms was sharply elevated under ultrasound irradiation, achieving a 4.0 log10 reduction of bacterial cells. The in vivo studies reveal that the MoSe2 NFs efficiently relieve the methicillin-resistant Staphylococcus aureus bacterial burden in mice under the control of ultrasound at a low power density. Moreover, because of the surface coating of antioxidant poly(ethyleneimine), the dual-driven catalysis of MoSe2 NFs was retarded in normal tissues to minimize the off-target damage and favor the wound healing process. Therefore, the cascade of piezoelectricity and enzyme-mimic activity in MoSe2 NFs reveals a dual-driven strategy for improving the performance of catalytic nanomaterials in the eradication of bacterial biofilms.

Y. Yu, Lei Tan, Zhaoyang Li et al.

ACS Nano • 2021

Osteomyelitis, as a severe bone disease caused by bacterial infection, can result in lifelong disability or fatal sepsis. Considering that the infection is stubborn and deep-sited in bone tissue, in situ and rapid treatments for osteomyelitis remain a significant challenge. Herein, we prepare an ultrasound (US)-activated single-atom catalyst that consists of a Au nanorod (NRs)-actuated single-atom-doped porphyrin metal-organic framework (HNTM-Pt@Au) and red cell membrane (RBC), which can efficiently treat methicillin-resistant Staphylococcus aureus (MRSA)-infected osteomyelitis under US. Besides the outstanding performance in the field of photocatalysis, we find that single atoms (such as Pt, Au, Cu) also improve the sonocatalytic ability of the sonosensitizer. Due to the strong electron-trapping and oxygen adsorption capacity, the Pt single atom endows RBC-HNTM-Pt@Au with an excellent sonocatalytic activity. It shows an excellent antibacterial performance with an antibacterial efficiency of 99.9% toward MRSA under 15 min of US irradiation. Meanwhile, the RBC-HNTM-Pt@Au can be propelled directionally under US and thus dynamically neutralize the secreted toxins. The MRSA-infected osteomyelitis in rat tibia was successfully treated, which shows negligible bone loss, reduced inflammation response, and great biocompatibility. This work presents an efficient sonodynamic therapy for the treatment of deep tissue infections via a multifunctional single-atom catalyst.

Xavier Arqué, Marcelo D. T. Torres, Tania Patiño et al.

ACS Nano • 2022

The increasing resistance of bacteria to existing antibiotics constitutes a major public health threat globally. Most current antibiotic treatments are hindered by poor delivery to the infection site, leading to undesired off-target effects and drug resistance development and spread. Here, we describe micro- and nanomotors that effectively and autonomously deliver antibiotic payloads to the target area. The active motion and antimicrobial activity of the silica-based robots are driven by catalysis of the enzyme urease and antimicrobial peptides, respectively. These antimicrobial motors show micromolar bactericidal activity in vitro against different Gram-positive and Gram-negative pathogenic bacterial strains and act by rapidly depolarizing their membrane. Finally, they demonstrated autonomous anti-infective efficacy in vivo in a clinically relevant abscess infection mouse model. In summary, our motors combine navigation, catalytic conversion, and bactericidal capacity to deliver antimicrobial payloads to specific infection sites. This technology represents a much-needed tool to direct therapeutics to their target to help combat drug-resistant infections.

Sheng Dong, Tian‐Di Wei, Xiulan Chen et al.

Journal of Biological Chemistry • 2014

Background: The maturation and catalysis mechanisms of the PL18 alginate lyases have not yet been reported. Results: The N-terminal extension in the precursor of PL18, aly-SJ02, helped the catalytic domain fold correctly. Key residues for substrate recognition and catalysis were determined. Conclusion: The catalytic mechanism of aly-SJ02 is proposed. Significance: This study provides the foremost insight into maturation and catalysis of PL18 alginate lyases. Bacterial alginate lyases, which are members of several polysaccharide lyase (PL) families, have important biological roles and biotechnological applications. The mechanisms for maturation, substrate recognition, and catalysis of PL18 alginate lyases are still largely unknown. A PL18 alginate lyase, aly-SJ02, from Pseudoalteromonas sp. 0524 displays a β-jelly roll scaffold. Structural and biochemical analyses indicated that the N-terminal extension in the aly-SJ02 precursor may act as an intramolecular chaperone to mediate the correct folding of the catalytic domain. Molecular dynamics simulations and mutational assays suggested that the lid loops over the aly-SJ02 active center serve as a gate for substrate entry. Molecular docking and site-directed mutations revealed that certain conserved residues at the active center, especially those at subsites +1 and +2, are crucial for substrate recognition. Tyr353 may function as both a catalytic base and acid. Based on our results, a model for the catalysis of aly-SJ02 in alginate depolymerization is proposed. Moreover, although bacterial alginate lyases from families PL5, 7, 15, and 18 adopt distinct scaffolds, they share the same conformation of catalytic residues, reflecting their convergent evolution. Our results provide the foremost insight into the mechanisms of maturation, substrate recognition, and catalysis of a PL18 alginate lyase.

T. V. Zharova, V. G. Grivennikova, V. Borisov

International Journal of Molecular Sciences • 2023

F1·Fo-ATP synthases/ATPases (F1·Fo) are molecular machines that couple either ATP synthesis from ADP and phosphate or ATP hydrolysis to the consumption or production of a transmembrane electrochemical gradient of protons. Currently, in view of the spread of drug-resistant disease-causing strains, there is an increasing interest in F1·Fo as new targets for antimicrobial drugs, in particular, anti-tuberculosis drugs, and inhibitors of these membrane proteins are being considered in this capacity. However, the specific drug search is hampered by the complex mechanism of regulation of F1·Fo in bacteria, in particular, in mycobacteria: the enzyme efficiently synthesizes ATP, but is not capable of ATP hydrolysis. In this review, we consider the current state of the problem of “unidirectional” F1·Fo catalysis found in a wide range of bacterial F1·Fo and enzymes from other organisms, the understanding of which will be useful for developing a strategy for the search for new drugs that selectively disrupt the energy production of bacterial cells.

Chuan Liu, Xuanping Zhao, Zichao Wang et al.

Journal of Nanobiotechnology • 2023

Bacterial wound infections are a serious threat due to the emergence of antibiotic resistance. Herein, we report an innovative hybrid nanozyme independent of antibiotics for antimicrobial wound healing. The hybrid nanozymes are fabricated from ultra-small Au NPs via in-situ growth on metal-organic framework (MOF)-stabilised Fe_3O_4 NPs (Fe_3O_4@MOF@Au NPs, FMA NPs). The fabricated hybrid nanozymes displayed synergistic peroxidase (POD)-like activities. It showed a remarkable level of hydroxyl radicals (·OH) in the presence of a low dose of H_2O_2 (0.97 mM). Further, the hybrid FMA nanozymes exhibited excellent biocompatibility and favourable antibacterial effects against both Gram-negative (Escherichia coli) and Gram-positive ( Staphylococcus aureus ) bacteria. The animal experiments indicated that the hybrid nanozymes promoted wound repair with adequate biosafety. Thus, the well-designed hybrid nanozymes represent a potential strategy for healing bacterial wound infections, without any toxic side effects, suggesting possible applications in antimicrobial therapy.

Nilmadhab Chakrabarti, Christopher Ing, Jian Payandeh et al.

Proceedings of the National Academy of Sciences • 2013

<jats:p> Determination of a high-resolution 3D structure of voltage-gated sodium channel Na <jats:sub>V</jats:sub> Ab opens the way to elucidating the mechanism of ion conductance and selectivity. To examine permeation of Na <jats:sup>+</jats:sup> through the selectivity filter of the channel, we performed large-scale molecular dynamics simulations of Na <jats:sub>V</jats:sub> Ab in an explicit, hydrated lipid bilayer at 0 mV in 150 mM NaCl, for a total simulation time of 21.6 μs. Although the cytoplasmic end of the pore is closed, reversible influx and efflux of Na <jats:sup>+</jats:sup> through the selectivity filter occurred spontaneously during simulations, leading to equilibrium movement of Na <jats:sup>+</jats:sup> between the extracellular medium and the central cavity of the channel. Analysis of Na <jats:sup>+</jats:sup> dynamics reveals a knock-on mechanism of ion permeation characterized by alternating occupancy of the channel by 2 and 3 Na <jats:sup>+</jats:sup> ions, with a computed rate of translocation of (6 ± 1) × 10 <jats:sup>6</jats:sup> ions⋅s <jats:sup>−1</jats:sup> that is consistent with expectations from electrophysiological studies. The binding of Na <jats:sup>+</jats:sup> is intimately coupled to conformational isomerization of the four E177 side chains lining the extracellular end of the selectivity filter. The reciprocal coordination of variable numbers of Na <jats:sup>+</jats:sup> ions and carboxylate groups leads to their condensation into ionic clusters of variable charge and spatial arrangement. Structural fluctuations of these ionic clusters result in a myriad of ion binding modes and foster a highly degenerate, liquid-like energy landscape propitious to Na <jats:sup>+</jats:sup> diffusion. By stabilizing multiple ionic occupancy states while helping Na <jats:sup>+</jats:sup> ions diffuse within the selectivity filter, the conformational flexibility of E177 side chains underpins the knock-on mechanism of Na <jats:sup>+</jats:sup> permeation. </jats:p>

Glenda Garvey

Journal of Neurosurgery • 1983

<jats:p content-type="fine-print">✓ Investigative work continues to provide guidance toward more rational management of bacterial meningitis and bacterial brain abscess. An increased understanding of the host's response in cases of bacterial meningitis has established that diffusibility of an antibiotic into the cerebrospinal fluid (CSF) is necessary, but is not sufficient for microbial cure. The antibiotic must also have a bactericidal effect on the pathogen. Meningitis after neurosurgery may be caused by Gram-negative aerobic bacilli. In some of these cases the newer cephalosporin antibiotics may be a useful advance. Meningitis complicating ventricular CSF shunts presents a paradigm for the problem of eradicating foreign body-related infections. Studies of the interaction of the host, the organism, and the shunt material offer some explanation for the limited efficacy of antibiotics observed in this setting. There have been advances in microbial definition of bacterial brain abscess. The identification of <jats:italic>Bacteroides fragilis</jats:italic> as a pathogen in certain brain abscesses has established a role for a newly available antibiotic, metronidazole. The study of the pathological distinction between cerebritis and frank abscess is clarifying two clinical characteristics of brain abscess: the limited success of antibiotic treatment and the increase in intracranial pressure. Computerized tomography has offered a valuable clinical “look” at brain abscesses; however, there are still problems in correlating the scan images with the evolving pathogical process.</jats:p>

Zhen Jia

Focus on Bacterial Biofilms • 0

<jats:p>Biofilm refers to a viable bacterial community wrapped in self-produced extracellular polymeric substances (EPS) matrix. As bacteria shielded by EPS are viable and can resist broad hostile environments and antimicrobial agents, biofilm poses a massive challenge to industries and human health. Currently, biofilm has accounted for widespread and severe safety issues, infections, and economic loss. Various antifouling strategies have been designed and developed to prevent biofilm formation. As bacterial biofilm is perceived as a dynamic multistage process in which bacterial attachment on solid surfaces is the prerequisite for biofilm formation, the interference with the attachment is the most promising environmentally benign option to antifouling. The chapter summarizes and discusses the antifouling strategies that interfere with the adhesion between bacteria and substrate surfaces. These strategies primarily focus on modifying the substrate surface’s topographical and physicochemical properties.</jats:p>

Jinjin Shen, Xiaoming Zhou, Yuanyue Shan et al.

Nature Communications • 0

<jats:title>Abstract</jats:title><jats:p>The ability to detect low numbers of microbial cells in food and clinical samples is highly valuable but remains a challenge. Here we present a detection system (called ‘APC-Cas’) that can detect very low numbers of a bacterial pathogen without isolation, using a three-stage amplification to generate powerful fluorescence signals. APC-Cas involves a combination of nucleic acid-based allosteric probes and CRISPR-Cas13a components. It can selectively and sensitively quantify <jats:italic>Salmonella</jats:italic> Enteritidis cells (from 1 to 10<jats:sup>5</jats:sup> CFU) in various types of samples such as milk, showing similar or higher sensitivity and accuracy compared with conventional real-time PCR. Furthermore, APC-Cas can identify low numbers of <jats:italic>S</jats:italic>. Enteritidis cells in mouse serum, distinguishing mice with early- and late-stage infection from uninfected mice. Our method may have potential clinical applications for early diagnosis of pathogens.</jats:p>

Meghna Thakur, Scott N. Dean, Julie C. Caruana et al.

Bioengineering • 0

<jats:p>The use of biological systems in manufacturing and medical applications has seen a dramatic rise in recent years as scientists and engineers have gained a greater understanding of both the strengths and limitations of biological systems. Biomanufacturing, or the use of biology for the production of biomolecules, chemical precursors, and others, is one particular area on the rise as enzymatic systems have been shown to be highly advantageous in limiting the need for harsh chemical processes and the formation of toxic products. Unfortunately, biological production of some products can be limited due to their toxic nature or reduced reaction efficiency due to competing metabolic pathways. In nature, microbes often secrete enzymes directly into the environment or encapsulate them within membrane vesicles to allow catalysis to occur outside the cell for the purpose of environmental conditioning, nutrient acquisition, or community interactions. Of particular interest to biotechnology applications, researchers have shown that membrane vesicle encapsulation often confers improved stability, solvent tolerance, and other benefits that are highly conducive to industrial manufacturing practices. While still an emerging field, this review will provide an introduction to biocatalysis and bacterial membrane vesicles, highlight the use of vesicles in catalytic processes in nature, describe successes of engineering vesicle/enzyme systems for biocatalysis, and end with a perspective on future directions, using selected examples to illustrate these systems’ potential as an enabling tool for biotechnology and biomanufacturing.</jats:p>

Tarek Dishisha, Sang-Hyun Pyo, R. Hatti-Kaul

Microbial Cell Factories • 2015

AbstractBackground3-Hydroxypropionic acid (3HP) and acrylic acid (AA) are industrially important platform- and secondary chemical, respectively. Their production from renewable resources by environment-friendly processes is desirable. In the present study, both chemicals were almost quantitatively produced from biodiesel-derived glycerol by an integrated process involving microbial and chemical catalysis.ResultsGlycerol was initially converted in a fed-batch mode of operation to equimolar quantities of 3HP and 1,3-propanediol (1,3PDO) under anaerobic conditions using resting cells of Lactobacillus reuteri as a biocatalyst. The feeding rate of glycerol was controlled at 62.5 mg/gCDW.h which is half the maximum metabolic flux of glycerol to 3HP and 1,3PDO through the L. reuteri propanediol-utilization (pdu) pathway to prevent accumulation of the inhibitory intermediate, 3-hydroxypronionaldehyde (3HPA). Subsequently, the cell-free supernatant containing the mixture of 3HP and 1,3PDO was subjected to selective oxidation under aerobic conditions using resting cells of Gluconobacter oxydans where 1,3PDO was quantitatively converted to 3HP in a batch system. The optimum conditions for the bioconversion were 10 g/L substrate and 5.2 g/L cell dry weight. Higher substrate concentrations led to enzyme inhibition and incomplete conversion. The resulting solution of 3HP was dehydrated to AA over titanium dioxide (TiO2) at 230 °C with a yield of >95 %.ConclusionsThe present study represents the first report on an integrated process for production of acrylic acid at high purity and -yield from glycerol through 3HP as intermediate without any purification step. The proposed process could have potential for industrial production of 3HP and AA after further optimization.Graphical abstractIntegrated three-step process for conversion of biodiesel glycerol to 3-hydroxypropionic acid (3HP) and acrylic acid (AA). Glycerol was initially converted to equimolar quantities of 3HP and 1,3-propanediol (1,3PDO) using resting cells of Lactobacillus reuteri. Subsequently, the cell-free supernatant containing the mixture of 3HP and 1,3PDO was subjected to selective oxidation using resting cells of Gluconobacter oxydans where 1,3PDO was quantitatively converted to 3HP. The resulting solution of 3HP was dehydrated to AA over titanium dioxide (TiO2) at 230 °C.

Zhichao Yu, Zhenjin Xu, Ruijin Zeng et al.

Angewandte Chemie International Edition • 2024

The global crisis of bacterial infections is exacerbated by the escalating threat of microbial antibiotic resistance. Nanozymes promise to provide ingenious solutions. Here, we reported a homogeneous catalytic structure of Pt nanoclusters with finely tuned metal-organic framework (ZIF-8) channel structures for the treatment of infected wounds. Catalytic site normalization showed that the active site of the Pt aggregates structure with fine-tuned pore modifications structure had a catalytic capacity of 14.903 ×105 min-1, which was 18.7 times higher than that of the Pt particles in monodisperse state in ZIF-8 (0.793 ×105 min-1). In situ tests revealed that the change from homocleavage to heterocleavage of hydrogen peroxide at the interface of the nanozyme was one of the key reasons for the improvement of nanozyme activity. Density-functional theory and kinetic simulations of the reaction interface jointly determine the role of the catalytic center and the substrate channel together. Metabolomics analysis showed that the developed nanozyme, working in conjunction with reactive oxygen species, could effectively block energy metabolic pathways within bacteria, leading to spontaneous apoptosis and bacterial rupture. This pioneering study elucidates new ideas for the regulation of artificial enzyme activity and provides new perspectives for the development of efficient antibiotic substitutes.

Feng Wang, Mingtong Wang, Ling Xu et al.

Foods • 2025

Flavor compounds are key determinants of food sensory quality, originating from natural sources, processing, or artificial additives. Although physical and chemical methods can effectively enhance food flavor, microbial fermentation and enzyme catalysis technology possess good potential in food flavor regulation due to their mild reaction conditions and high safety. In addition, the high efficiency and specificity of enzymes help to shorten the production cycle and accurately regulate food flavor. This review focuses on the application and regulation mechanism of bacteria, yeast, other fungi, and mixed microbe fermentation systems in flavor production. The utilization and catalytic reaction schemes of oxidoreductases, transferases, and hydrolases in flavor regulation are also deeply explored, and suggestions for the application of microbial fermentation and enzyme catalysis technology in flavor regulation are discussed.

Q. Pan, Bi-Lin Lai, Li-Juan Huang et al.

ACS Applied Materials &amp; Interfaces • 2022

The efficient and durable oxygen reduction reaction (ORR) catalyst is of great significance to boost power generation and pollutant degradation in microbial fuel cells (MFCs). Although transition metal-nitrogen-codoped carbon materials are an important class of ORR catalysts, copper-nitrogen-codoped carbon is not considered a suitable MFC cathode catalyst due to the insufficient performance and especially instability. Herein, we report a three-dimensional (3D) hierarchical porous copper, nitrogen, and boron codoped carbon (3DHP Cu-N/B-C) catalyst synthesized by the dual template method. The introduced B atom as an electron donor increases the electron density around the Cu-Nx active site, which significantly promotes the efficiency of the ORR process and stabilizes the active site by preventing demetallization. Thus, the 3DHP Cu-N/B-C catalyst exhibited excellent ORR performance with the half-wave potential of 0.83 V (vs reversible hydrogen electrode (RHE)) in a 0.1 M KOH electrolyte and 0.68 V (vs RHE) in a 50 mM PBS electrolyte. Meanwhile, 3DHP Cu-N/B-C had satisfactory stability with 94.16% current retention after 24 h of chronoamperometry test, which is better than that of 20% Pt/C. The MFCs using 3DHP Cu-N/B-C not only showed a maximum power density of up to 760.14 ± 19.03 mW m-2 but also operating durability of more than 50 days. Moreover, the 16S rDNA sequencing results presented that the 3DHP Cu-N/B-C catalyst had a positive effect on the microbial community of the MFC with more anaerobic electroactive bacteria in the anode biofilm and fewer aerobic bacteria in the cathode biofilm. This study provides a new approach for the development of Cu-based ORR electrocatalysts as well as guidance for the rational design of high-performance MFCs.

Nina Klos, Ole Osterthun, H. G. Mengers et al.

JACS Au • 2024

The chemical industry can now seize the opportunity to improve the sustainability of its processes by replacing fossil carbon sources with renewable alternatives such as CO2, biomass, and plastics, thereby thinking ahead and having a look into the future. For their conversion to intermediate and final products, different types of catalysts—microbial, enzymatic, and organometallic—can be applied. The first part of this review shows how these catalysts can work separately in parallel, each route with unique requirements and advantages. While the different types of catalysts are often seen as competitive approaches, an increasing number of examples highlight, how combinations and concatenations of catalysts of the complete spectrum can open new roads to new products. Therefore, the second part focuses on the different catalysts either in one-step, one-pot transformations or in reaction cascades. In the former, the reaction conditions must be conflated but purification steps are minimized. In the latter, each catalyst can work under optimal conditions and the “hand-over points” should be chosen according to defined criteria like minimal energy usage during separation procedures. The examples are discussed in the context of the contributions of catalysis to the envisaged (bio)economy.

Chengcheng Feng, You Wu, Zizhe Cai et al.

Journal of the Science of Food and Agriculture • 2024

BACKGROUND Flax lignan has attracted much attention due to its potential bioactivities. However, the bioavailability of Secoisolariciresinol diglucoside(SDG), the main lignan in flaxseed, depends on the bioconversion by the colon bacteria. Lactic acid bacteria (LAB) with β-glucosidase activity found wide application in preparing bioactive aglycone. RESULTS LAB strains with good β-glucosidase activity were isolated from fermented tofu. Their bioconversion of flax lignan extract was investigated by resting cell catalysis and microbial fermentation, and the metabolism of SDG by Lactiplantibacillus plantarum C5 following fermentation was characterized by widely targeted metabolomics. Five L. plantarum strains producing β-glucosidase with broad substrate specificity were isolated and identified, and they all can transform SDG into Secoisolariciresinol (SECO). L. plantarum C5 resting cell reached a maximum SDG conversion of 49.19 ± 3.75%, and SECO generation of 21.49 ± 1.32% (0.215 ± 0.013 mM) at an SDG substrate concentration of 1 mM and 0.477 ± 0.003 mM SECO was produced at 4 mM within 24 h. While sixteen flax lignan metabolites were identified following the fermentation of SDG extract by L. plantarum C5, among them, four were produced following the fermentation: SECO, demethyl-SECO, demethyl-dehydroxy-SECO, and isolariciresinol. Moreover, seven lignans increased significantly. CONCLUSION Fermentation significantly increased the profile and level of flax lignan metabolites, and the resting cell catalysis benefits from higher bioconversion efficiency and more straightforward product separation. Resting cell catalysis and microbial fermentation of flax lignan extract by the isolated β-glucosidase production L. plantarum could be potentially applied in preparing flax lignan ingredients and fermented flaxseed. This article is protected by copyright. All rights reserved.