Synthesis Of Acetate Research Articles

An integrated microbiome- and metabolome-genome-wide association study reveals the role of heritable ruminal microbial carbohydrate metabolism in lactation performance in Holstein dairy cows

BackgroundDespite the growing number of studies investigating the connection between host genetics and the rumen microbiota, there remains a dearth of systematic research exploring the composition, function, and metabolic traits of highly heritable rumen microbiota influenced by host genetics. Furthermore, the impact of these highly heritable subsets on lactation performance in cows remains unknown. To address this gap, we collected and analyzed whole-genome resequencing data, rumen metagenomes, rumen metabolomes and short-chain fatty acids (SCFAs) content, and lactation performance phenotypes from a cohort of 304 dairy cows.ResultsThe results indicated that the proportions of highly heritable subsets (h2 ≥ 0.2) of the rumen microbial composition (55%), function (39% KEGG and 28% CAZy), and metabolites (18%) decreased sequentially. Moreover, the highly heritable microbes can increase energy-corrected milk (ECM) production by reducing the rumen acetate/propionate ratio, according to the structural equation model (SEM) analysis (CFI = 0.898). Furthermore, the highly heritable enzymes involved in the SCFA synthesis metabolic pathway can promote the synthesis of propionate and inhibit the acetate synthesis. Next, the same significant SNP variants were used to integrate information from genome-wide association studies (GWASs), microbiome-GWASs, metabolome-GWASs, and microbiome-wide association studies (mWASs). The identified single nucleotide polymorphisms (SNPs) of rs43470227 and rs43472732 on SLC30A9 (Zn2+ transport) (P < 0.05/nSNPs) can affect the abundance of rumen microbes such as Prevotella_sp., Prevotella_sp._E15-22, Prevotella_sp._E13-27, which have the oligosaccharide-degradation enzymes genes, including the GH10, GH13, GH43, GH95, and GH115 families. The identified SNPs of chr25:11,177 on 5s_rRNA (small ribosomal RNA) (P < 0.05/nSNPs) were linked to ECM, the abundance alteration of Pseudobutyrivibrio_sp. (a genus that was also showed to be linked to the ECM production via the mWASs analysis), GH24 (lysozyme), and 9,10,13-TriHOME (linoleic acid metabolism). Moreover, ECM, and the abundances of Pseudobutyrivibrio sp., GH24, and 9,10,13-TRIHOME were significantly greater in the GG genotype than in the AG genotype at chr25:11,177 (P < 0.05). By further the SEM analysis, GH24 was positively correlated with Pseudobutyrivibrio sp., which was positively correlated with 9,10,13-triHOME and subsequently positively correlated with ECM (CFI = 0.942).ConclusionOur comprehensive study revealed the distinct heritability patterns of rumen microbial composition, function, and metabolism. Additionally, we shed light on the influence of host SNP variants on the rumen microbes with carbohydrate metabolism and their subsequent effects on lactation performance. Collectively, these findings offer compelling evidence for the host-microbe interactions, wherein cows actively modulate their rumen microbiota through SNP variants to regulate their own lactation performance.C1VA69ck9huqCRa2wNrTKWVideo

Mechanistic Insights on Coverage-Dependent Selectivity Limitations in Vinyl Acetate Synthesis.

Developing improved catalysts for sustainable chemical processes often involves understanding atomistic origins of catalytic activity, selectivity, and stability. Using density functional theory and steady-state kinetic analyses, we probe the elementary steps that form decomposition products that limit selectivity in vinyl acetate (VA) synthesis on Pd surfaces covered with acetate species. Acetate formation and coupling with ethylene control the VA formation catalytic cycle and steady-state coverage, but acetate and ethylene can separately decompose to form CO2. Both decompositions involve initial C-H activations at acetate vacancies, followed by additional C-H activations and eventual C-O formations and C-C cleavages involving reactions with molecular oxygen. Acetate decomposition paths with non-oxidative kinetically-relevant steps exhibit similar free energy barriers to oxidative paths. In contrast, the non-oxidative ethylene path involving an ethylidyne intermediate exhibits a much lower barrier than paths with oxidative kinetically-relevant steps. Ethylene decomposition is very facile at low coverages but is more coverage-sensitive, leading to similar decomposition and VA formation barriers at coverages accessible at steady state, which is consistent with moderate VA selectivity in measurements and ethylene vs. acetate decomposition contributions assessed from regressed kinetic parameters. These insights provide a detailed framework for describing VA synthesis rates and selectivity on metallic catalyst surfaces.

Upgrading algae waste into 3-D bio-cathode to enhance acetate synthesis by microbial electrosynthesis

Microbial electrosynthesis (MES) technology has already obtained widespread attraction for CO2 conversion and high value-added chemicals production. However, MES has been challenged by the high cost and poor electrocatalytic activity of bio-cathodes. This study proposed a solution for upgrading algae waste into 3-D porous block bio-cathode through the coupling of template modification with phenolic resin cross-linking. The resulting porous algal electrode (PAE) exhibited an enhanced structure with 3.22 % N-doped, high content of oxygen-containing functional groups (22.67 %), and macropore structure with an average pore size of 70 µm. Consequently, the PAE showed impressive acetate synthesis performance, reaching a remarkable 1020.86 mol/m3 and surpassing the commercial carbon felts (CF) by 1.7-fold at −1.1 V (vs. Ag/AgCl). Mechanistic studies indicated that microbial loading capacity in PAE was 1.31 times higher than that in CF. Additionally, the improved N-doped and oxygen-containing functional groups enhanced direct and indirect electron transfer between the electrode and the microorganisms, respectively. All of which contributed to the efficient synthesis of acetate. Therefore, this study not only developed an innovative 3-D porous bio-cathode for efficient CO2 conversion and high value-added chemicals production, but also provided a promising sustainable strategy for algae waste treatment and recycling.

Catalytic behavior, electronic structure and spectroscopic (FT-IR, Raman, UV–vis) properties for the new ionic liquid imidazolium hydrogen sulfate

Catalytic performance, chemical reactivity, vibrational modes and electronic transitions of the ion pair [H–Im]+[HSO4]– were investigated in the current paper. Hence, a combined experimental (Hammett acidity function, infrared, Raman and ultraviolet-visible spectroscopies) and theoretical (molecular electrostatic potential surface, reduced density gradient, frontier molecular orbital analysis, quantum theory of atoms in molecules, net atomic charges, global and local reactivity descriptors) study was conducted. In terms of the catalytic performance, the acetic acid esterification with butanol was evaluated. Important kinetic (rate constant, activation energy, pre-exponential factor) and thermodynamic (enthalpy, entropy, Gibbs free energy barrier) factors for ester production as a function of the temperature and catalyst loading have been determined. Results revealed intensive electron density distribution in [H–Im]+[HSO4]– due to chemical interactions between the cationic and anionic moieties. These bonds were established as electrostatic in nature. The pronounced charge transfers within [H–Im]+[HSO4]– managed the title compound acidity (H0) and its catalytic behavior towards butyl acetate synthesis. Using the thermodynamic and kinetic measurements, a mechanism for acetic acid esterification with butanol in the presence of imidazolium hydrogen sulfate ionic liquid was offered.

Cellulose nanocrystal extraction from tissue paper wastes using different extraction methods and cellulose acetate production

ABSTRACT This paper examines the feasibility of extracting cellulose from tissue paper wastes (TPW’s) using several methods: sonication (SC), subcritical (SU), microwave (MC), and microwave with diluted acid (MA). The chemical characterisation and morphological properties of nanocrystal cellulose were investigated using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and scanning electron microscopy with energy dispersive X-Ray analysis (SEM-EDX). TPW’s have a relatively high crystallinity index (CrI = 61.02%). It was found to be lower than that for cellulose extracted using SU and SC MC, MA methods, where CrI to 65.65%, 68.07%, 69.21% and 73.42%, respectively. The MA method yielded cellulose with the highest CrI and altered surface morphology. This cellulose was selected for cellulose acetate synthesis. After acetylation, the CrI decreased to 61.45%, and the morphological aspect was changed. In conclusion, nanocrystal cellulose was successfully extracted from TPW’s and effectively changed to its esterified form.

Efficient synthesis of cellulose acetate through one-step homogeneous acetylation of cotton cellulose in binary ionic liquids

Cellulose acetate (CA) is an important cellulose derivative with a wide range of applications. To adopt a more efficient and environmentally friendly method to synthesize cellulose acetate, a binary ionic liquid mixture of 1-butyl-3-methylimidazole chloride salt (BmimCl) and 1-butyl-3-methyldihydroimidazole phosphate (BmimH2PO4) was used. Compared to the conventional methods, this approach didn't require pre-activation of cellulose and the process of homogeneous acetylation proceeded without a catalyst. By simply adjusting the reaction conditions, cellulose acetate with a degree of substitution (DS) in the range of 0.83–3.0 was produced by one-step homogeneous acetylation without hydrolysis. Furthermore, the cellulose acetate film produced by solvent casting exhibited smooth surface characteristics, 95 % transparency, and 57.9 MPa tensile strength. Therefore, this study highlights the importance of using binary ionic liquid mixtures for facile synthesis of cellulose acetate. Due to their excellent transparency and mechanical properties, newly synthesized cellulose acetate films could replace commercial films.

Synthesis of the pyruvic acid acetal containing tetrasaccharide repeating unit corresponding to the K82 capsular polysaccharide of Acinetobacter baumannii LUH5534 strain

An efficient synthetic strategy has been developed to achieve a pyruvic acid acetal containing tetrasaccharide repeating unit corresponding to the K82 capsular polysaccharide of Acinetobacter baumannii LUH5534 strain in very good yield. The synthetic scheme involves the use of suitably functionalized monosaccharide thioglycosides as glycosyl donors and a combination of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) as thiophilic glycosylation activator to furnish satisfactory yield of the products with appropriate stereochemistry at the glycosidic linkages. Incorporation of the (R)-pyruvic acid acetal in the D-galactose moiety was achieved in very good yield by the treatment of the diol derivative with methyl 2,2-bis(p-methylphenylthio)propionate in the presence of a combination of NIS and triflic acid.

Synergistic role of carbon quantum dots on biohydrogen production

Biohybrid system has their distinct ability to improve microbial fermentation. This study demonstrates the role of surface-doped carbon quantum dots (CQDs) on dark fermentative biohydrogen production using lactobacillus organic-hybrid biocatalyst. Herein, nitrogen-doped carbon quantum dots (N-CQDs) with < 5 nm (having a surface charge of +2.6 mV) and un-doped carbon quantum dots (CQDs) (having a surface charge of −4.5 mV) were synthesized via chemical assisted process. Subsequently, the biohybrid systems were constructed via augmentation of N-CQDs and CQDs with Lactobacillus delbreuckii and assessed for biohydrogen production. The results revealed that both the biohybrid systems (N-CQDs- Lactobacillus delbreuckii and CQDs- Lactobacillus delbreuckii) provided improved hydrogen production than that of the native bacterial strain. Interestingly, the obtained N-CQDs- Lactobacillus delbreuckii system provided the maximum hydrogen yield of 2.01 mol/mol hexose, followed by 1.86 mol/mol hexose from CQDs- Lactobacillus delbreuckii, which is about 33 % and 19 % higher than the bare bacterial strain. The electron transfer and metabolic alteration of microbes by carbon quantum dots were assessed using cyclic voltammetry (CV) and VFA production. It was concluded that the improved bio-hydrogen production from N-CQDs- Lactobacillus delbreuckii is attributed to enhanced electron transfer, which regulates the central metabolic pathway of acetate and butyrate synthesis with the least production of lactate and other reduced end product formation.

Systems biology of electrogenic Pseudomonas putida - multi-omics insights and metabolic engineering for enhanced 2-ketogluconate production

BackgroundPseudomonas putida KT2440 has emerged as a promising host for industrial bioproduction. However, its strictly aerobic nature limits the scope of applications. Remarkably, this microbe exhibits high bioconversion efficiency when cultured in an anoxic bio-electrochemical system (BES), where the anode serves as the terminal electron acceptor instead of oxygen. This environment facilitates the synthesis of commercially attractive chemicals, including 2-ketogluconate (2KG). To better understand this interesting electrogenic phenotype, we studied the BES-cultured strain on a systems level through multi-omics analysis. Inspired by our findings, we constructed novel mutants aimed at improving 2KG production.ResultsWhen incubated on glucose, P. putida KT2440 did not grow but produced significant amounts of 2KG, along with minor amounts of gluconate, acetate, pyruvate, succinate, and lactate. 13C tracer studies demonstrated that these products are partially derived from biomass carbon, involving proteins and lipids. Over time, the cells exhibited global changes on both the transcriptomic and proteomic levels, including the shutdown of translation and cell motility, likely to conserve energy. These adaptations enabled the cells to maintain significant metabolic activity for several weeks. Acetate formation was shown to contribute to energy supply. Mutants deficient in acetate production demonstrated superior 2KG production in terms of titer, yield, and productivity. The ∆aldBI ∆aldBII double deletion mutant performed best, accumulating 2KG at twice the rate of the wild type and with an increased yield (0.96 mol/mol).ConclusionsBy integrating transcriptomic, proteomic, and metabolomic analyses, this work provides the first systems biology insight into the electrogenic phenotype of P. putida KT2440. Adaptation to anoxic-electrogenic conditions involved coordinated changes in energy metabolism, enabling cells to sustain metabolic activity for extended periods. The metabolically engineered mutants are promising for enhanced 2KG production under these conditions. The attenuation of acetate synthesis represents the first systems biology-informed metabolic engineering strategy for enhanced 2KG production in P. putida. This non-growth anoxic-electrogenic mode expands our understanding of the interplay between growth, glucose phosphorylation, and glucose oxidation into gluconate and 2KG in P. putida.

Metabolic-methane mitigation by combination of probiotic Escherichia coli strain Nissle 1917 and biochar in rumen fluid in vitro fermentation of dairy cow

In response to climate change, there have been various trials to reduce methane emissions from ruminant animals in the livestock industry, and one of the typical candidates is probiotics used as feed additives. We employed Escherichia coli Nissle 1917 (EcN) as a promising probiotic for the reduction of methane emissions and investigated the molecular mechanism of methane-reducing effects using CRISPR/Cas9. The anaerobic culture of EcN with biochar (BC) could significantly increase acetate and hydrogen production. Additionally, RNA-seq analysis revealed an upregulation in the expression of acetate synthesis genes, namely, pta, poxB, and ackA. Subsequently, treatment of rumen fluid with EcN significantly decreased methane and increased acetate and propionate production, as observed through the analysis of short-chain fatty acids, and these effects could accelerate with additional supplementation of BC. The observation of changes in the microbial composition of rumen fluid following treatment with EcN and BC was made through rumen metagenomic analysis and RT-qPCR. The results revealed an increase in acetogen and propionate producing bacteria abundance and a decrease in methanogen abundance. Based on these findings, the CRISPR/Cas9 system was employed to elucidate the molecular mechanism of the methane-reducing capability of EcN. Gene deletion was performed targeting the genes poxB, ackA, and pta as key factors in acetate pathway in E. coli. The knockout of poxB, ackA, and pta could lead to the elimination of the methane-reduction of EcN as well as acetate-producing abilities. Collectively, the methane reduction ability of EcN in rumen fluid is associated with its acetate production capability, and the addition of BC significantly enhances methane mitigation capability of EcN.

Enhanced microbial electrosynthesis performance with 3-D algal electrodes under high CO2 sparging: Superior biofilm stability and biocathode-plankton interactions

Microbial electrosynthesis (MES) shows great promise for converting CO2 into high-value chemicals. However, cathode biofilm erosion by high CO2 sparging and the unclear role of plankton in MES hinders the continuous improvement of its performance. This study aims to enhance biofilm resistance and improve interactions between bio-cathode and plankton by upgrading waste algal biomass into 3-D porous algal electrode (PAE) with rough surface. Results showed that the acetate synthesis of PAE under 20 mL/min CO2 sparging (PAE-20) was up to 3330.61 mol/m3, 4.63 times that of carbon felt under the same conditions (CF-20). The microbial loading of PAE-20 biofilm was twice that of CF-20. Furthermore, higher cumulative abundance of functional microorganisms was observed in plankton of PAE-20 (55 %), compared to plankton of CF-20 (14 %), and enhanced biocathode-plankton interactions significantly suppressed acetate consumption. Thus, this efficient and sustainable 3-D electrode advances MES technology and offers new perspectives for waste biomass recycling.

Engineering a non-oxidative glycolysis pathway in escherichia coli for high-level citramalate production

BackgroundMethyl methacrylate (MMA) is a key precursor of polymethyl methacrylate, extensively used as a transparent thermoplastic in various industries. Conventional MMA production poses health and environmental risks; hence, citramalate serves as an alternative bacterial compound precursor for MMA production. The highest citramalate titer was previously achieved by Escherichia coli BW25113. However, studies on further improving citramalate production through metabolic engineering are limited, and phage contamination is a persistent problem in E. coli fermentation.ResultsThis study aimed to construct a phage-resistant E. coli BW25113 strain capable of producing high citramalate titers from glucose. First, promoters and heterologous cimA genes were screened, and an effective biosynthetic pathway for citramalate was established by overexpressing MjcimA3.7, a mutated cimA gene from Methanococcus jannaschii, regulated by the BBa_J23100 promoter in E. coli. Subsequently, a phage-resistant E. coli strain was engineered by integrating the Ssp defense system into the genome and mutating key components of the phage infection cycle. Then, the strain was engineered to include the non-oxidative glycolysis pathway while removing the acetate synthesis pathway to enhance the supply of acetyl-CoA. Furthermore, glucose utilization by the strain improved, thereby increasing citramalate production. Ultimately, 110.2 g/L of citramalate was obtained after 80 h fed-batch fermentation. The citramalate yield from glucose and productivity were 0.4 g/g glucose and 1.4 g/(L·h), respectively.ConclusionThis is the highest reported citramalate titer and productivity in E. coli without the addition of expensive yeast extract and additional induction in fed-bath fermentation, emphasizing its potential for practical applications in producing citramalate and its derivatives.

Synthesis of novel pyrazole acetals of andrographolide and isoandrographolide as potent anticancer agents.

Globally, cancer is the most prevalent chronic disease-related cause of death. Although there are many anticancer drugs, some of them have adverse effects. Due to their limited side effects, natural products are preferred over synthetic drugs. Andrographolide and its derivatives are known to be potent anticancer agents. In this context, sixteen novel 3,19-(NH-3-aryl-pyrazole) acetals of andrographolide and isoandrographolide (1a-1h, 2a-2g, 2i) from 3-aryl-1-H-pyrazole-4-carboxaldehydes (a-i) were synthesized. All the synthesized compounds were characterized using 1H NMR, 13C NMR, HRMS, FT-IR, and UV-vis spectroscopy. All the compounds were evaluated against a panel of 60 different human cancer cell lines for their anticancer potential at NCI, USA. Four compounds, having promising GI50s (50% growth inhibitory activity) on all 60-cell lines were selected for further in vitro studies. Out of these four compounds, compound 1g exhibited the best IC50 (3.08 μM) against the colon cancer cell line, HCT-116. Cell cycle analysis, annexin V-FITC/PI, and ROS assays revealed that the apoptosis of HCT-116 cells induced by compound 1g could be mainly attributed to the elevated levels of intracellular ROS. Further, the structure-activity relationship revealed that the pyrazole moiety of andrographolide plays a key role in their anticancer properties. These compounds were further examined for in silico ADMET and Lipinski characteristics to assess their potential as lead compounds.

Metal-free functionalized carbon nitride as a photocatalyst driven by sunlight for acetal synthesis and selective regeneration of NAD(P)H cofactor.

Nicotinamide Adenine Dinucleotide Phosphate (NAD(P)H) plays an important role in numerous biologically significant redox reactions. The photochemical restoration of its oxidized form (NAD(P)+) under physiological conditions is intriguing in the context of integrated photo and catalysis. Herein, we report the functionalized graphitic carbon-based solar light active photocatalyst by doping boron and fluorine in the native graphitic carbon nitride (GCN) (nonfunctionalized) for the regeneration of enzymatically visible light active coenzyme and in photo-acetalization reactions. The metal-free functionalized photocatalyst systems such as BFGCN-x leads to higher yield NADH and NADPH regeneration. They are also capable of catalyzing acetal reactions in the absence of any Lewis and Bronsted acids. The current research endeavor provides the advancement and the application of functionalized GCN-based photocatalysts for NADH (61.89%), NADPH (59.84%) regeneration, and photo-acetalization reactions.

Mechanistic insights into ethylene catalytic combustion and CO2 formation in vinyl acetate synthesis

Vinyl acetate is a crucial monomer for the production of polyvinyl alcohol and polyvinyl acetate, with extensive applications in the photovoltaic and pharmaceutical industries. CO2 is the primary by-product in the synthesis of vinyl acetate, significantly burdening the separation process and impacting the ecological environment. Reducing CO2 generation at the source is an effective solution. In the vinyl acetate synthesis process, CO2 is primarily produced through the catalytic combustion of ethylene. However, the reaction mechanism of ethylene catalytic combustion on Pd-based catalysts in vinyl acetate synthesis remains incomplete, with existing mechanisms presenting certain limitations. Therefore, further investigation into the reaction mechanism of ethylene catalytic combustion leading to CO2 formation on Pd-based catalysts is necessary.This study employs density functional theory to calculate the reaction mechanism of ethylene catalytic combustion on the Pd(100) surface, obtaining elementary reaction kinetics data. Based on these data, the kinetic Monte Carlo method was used to investigate the reaction process of ethylene catalytic combustion, revealing the predominant pathway for CO2 formation. This research provides targeted strategies for catalyst modification. It aims to improve the understanding of the reaction mechanism of ethylene catalytic combustion in vinyl acetate synthesis, reduce the consumption of ethylene in by-product formation, enhance vinyl acetate yield and ethylene utilization, and ultimately decrease CO2 production, thereby lowering carbon emissions.

Chiral Acetal-Based Stereo-Controlled Degradable Polymer Synthesis.

The precise synthesis of chiral polymers remains a significant challenge in polymer chemistry, particularly for applications in advanced biomedical and electronic materials. The development of degradable polymers is important for eco-friendly and advanced materials. Here, we introduce a stereo-controlled degradable polymer via cascade enyne metathesis polymerization and enantioselective acetal synthesis through Pd-catalyzed asymmetric hydroamination. This approach allows for the creation of chiral acetal-based polymers with controlled stereochemistry and degradability, highlighting their potential for use in drug delivery and electronic applications. This concept article reviews the background, development, and potential applications of these stereo-controlled degradable polymers.

Multi-omics analysis unravels chemical roadmap and genetic basis for peach fruit aroma improvement

Selection of fruits with enhanced health benefits and superior flavor is an important aspect of peach breeding. Understanding the genetic interplay between appearance and flavor chemicals remains a major challenge. We identify the most important volatiles contributing to consumer preferences for peach, thus establishing priorities for improving flavor quality. We quantify volatiles of a peach population consisting of 184 accessions and demonstrate major reductions in the important flavor volatiles linalool and Z-3-hexenyl acetate in red-fleshed accessions. We identify 474 functional gene regulatory networks (GRNs), among which GRN05 plays a crucial role in controlling both red flesh and volatile content through the NAM/ATAF1/2/CUC (NAC) transcription factor PpBL. Overexpressing PpBL results in reduced expression of PpNAC1, a positive regulator for Z-3-hexenyl acetate and linalool synthesis. Additionally, we identify haplotypes for three tandem PpAATs that are significantly correlated with reduced gene expression and ester content. We develop genetic resources for improvement of fruit quality.

Chemical Antiquity in Metabolism.

ConspectusLife is an exergonic chemical reaction. The same was true when the very first cells emerged at life's origin. In order to live, all cells need a source of carbon, energy, and electrons to drive their overall reaction network (metabolism). In most cells, these are separate pathways. There is only one biochemical pathway that serves all three needs simultaneously: the acetyl-CoA pathway of CO2 fixation. In the acetyl-CoA pathway, electrons from H2 reduce CO2 to pyruvate for carbon supply, while methane or acetate synthesis are coupled to energy conservation as ATP. This simplicity and thermodynamic favorability prompted Georg Fuchs and Erhard Stupperich to propose in 1985 that the acetyl-CoA pathway might mark the origin of metabolism, at the same time that Steve Ragsdale and Harland Wood were uncovering catalytic roles for Fe, Co, and Ni in the enzymes of the pathway. Subsequent work has provided strong support for those proposals.In the presence of Fe, Co, and Ni in their native metallic state as catalysts, aqueous H2 and CO2 react specifically to formate, acetate, methane, and pyruvate overnight at 100 °C. These metals (and their alloys) thus replace the function of over 120 enzymes required for the conversion of H2 and CO2 to pyruvate via the pathway and its cofactors, an unprecedented set of findings in the study of biochemical evolution. The reactions require alkaline conditions, which promote hydrogen oxidation by proton removal and are naturally generated in serpentinizing (H2-producing) hydrothermal vents. Serpentinizing hydrothermal vents furthermore produce natural deposits of native Fe, Co, Ni, and their alloys. These are precisely the metals that reduce CO2 with H2 in the laboratory; they are also the metals found at the active sites of enzymes in the acetyl-CoA pathway. Iron, cobalt and nickel are relicts of the environments in which metabolism arose, environments that still harbor ancient methane- and acetate-producing autotrophs today. This convergence indicates bedrock-level antiquity for the acetyl-CoA pathway. In acetogens and methanogens growing on H2 as reductant, the acetyl-CoA pathway requires flavin-based electron bifurcation as a source of reduced ferredoxin (a 4Fe4S cluster-containing protein) in order to function. Recent findings show that H2 can reduce the 4Fe4S clusters of ferredoxin in the presence of native iron, uncovering an evolutionary precursor of flavin-based electron bifurcation and suggesting an origin of FeS-dependent electron transfer in proteins. Traditionally discussed as catalysts in early evolution, the most common function of FeS clusters in metabolism is one-electron transfer, also in radical SAM enzymes, a large and ancient enzyme family. The cofactors and active sites in enzymes of the acetyl-CoA pathway uncover chemical antiquity in metabolism involving metals, methyl groups, methyl transfer reactions, cobamides, pterins, GTP, S-adenosylmethionine, radical SAM enzymes, and carbon-metal bonds. The reaction sequence from H2 and CO2 to pyruvate on naturally deposited native metals is maximally simple. It requires neither nitrogen, sulfur, phosphorus, RNA, ion gradients, nor light. Solid-state metal catalysts tether the origin of metabolism to a H2-producing, serpentinizing hydrothermal vent.

Bacillus paralicheniformis, an acetate-producing probiotic, alleviates ulcerative colitis via protecting the intestinal barrier and regulating the NLRP3 inflammasome

Ulcerative colitis (UC) presents a challenging scenario in digestive health, characterized by recurrent inflammation that is often hard to manage. Bacteria capable of producing short-chain fatty acids (SCFAs) play a pivotal role in mitigating UC symptoms, rendering them promising candidates for probiotic therapy. In this investigation, we assessed the impact of Bacillus paralicheniformis HMPM220325 on dextran sodium sulfate (DSS)-induced UC in mice. Genomic analysis of the strain revealed the presence of protease genes associated with acetate and butyrate synthesis, with acetic acid detected in its fermentation broth. Administration of B. paralicheniformis HMPM220325 to UC mice ameliorated pathological manifestations of the condition and restored intestinal barrier function. Furthermore, B. paralicheniformis HMPM220325 suppressed the activation of the NLRP3 inflammasome signaling pathway and modulated the composition of the intestinal microbiota. These findings shed significant light on the potential of B. paralicheniformis as a probiotic candidate, offering a novel avenue for the prevention and therapeutic intervention of colitis.

Single-Atom Alloy Formation via Reaction-Driven Catalyst Restructuring.

We demonstrate that single-atom alloy catalysts can be made by exposing physical mixtures of monometallic supported Cu and Pd catalysts to vinyl acetate (VA) synthesis reaction conditions. This reaction induces the formation of mobile clusters of metal diacetate species that drive extensive metal nanoparticle restructuring, leading to atomic dispersion of the precious metal, smaller nanoparticle sizes than the parent catalysts, and high activity and selectivity for both VA synthesis and ethanol dehydrogenation reactions. This approach is scalable and appears to be generalizable to other alloy catalysts.