Production Of Glycolic Acid Research Articles

Investigation of Bottleneck Enzyme Through Flux Balance Analysis to Improve Glycolic Acid Production in Escherichia coli.

Amid rising environmental concerns, attempts have been made to produce glycolic acid (GA) using microbial processes with renewable carbon resources instead of using chemicals. The Dahms pathway for GA production uses xylose as a substrate and consists of relatively simple enzymatic steps. However, employing it leads to a decrease in cell growth and GA productivity. Systematically identifying and addressing metabolic bottlenecks in the Dahms pathway are essential for efficient glycolic acid (GA) production have not yet been performed. Through metabolic flux balance analysis, we found that insufficient aldehyde dehydrogenase (AldA) activity lowers GA production and negatively affects cell growth due to reduced energy production. Thus, we discovered a novel AldA isolated from Buttiauxella agrestis (BaAldA) demonstrated a 1.69-fold lower KM and a 1.49-fold higher turnover rate (kcat/KM) than AldA from Escherichia coli (EcAldA). GA production in E. coli harboring BaAldA was 1.59 times higher than in the original strain. Fed-batch fermentation of E. coli harboring BaAldA produced 22.70g/L GA with a yield of 0.497g/gxylose (98.2% of the theoretical maximum yield in the Dahms pathway), showing a higher final yield for GA than previously reported in E. coli. Our novel BaAldA enzyme shows great potential for the production of GA using microorganisms or enzymes. Furthermore, our approach to identifying metabolic bottlenecks using flux balance analysis could be utilized to enhance the microbial production of various desirable products in future studies.

Manganese-Biochar Catalyst for Sustainable Glycolic Acid Production from Biomass-Derived Glucose and Oligosaccharides

Manganese-Biochar Catalyst for Sustainable Glycolic Acid Production from Biomass-Derived Glucose and Oligosaccharides

Green synthesis of glycolic acid through the electrocatalytic reduction of oxalic acid over black TiO2: An experimental and theoretical study

Herein, we present the electrocatalytic four-electron hydrogenation of oxalic acid into glycolic acid using black TiO2 as an electrocatalyst. Oxalic acid is an abundant compound found in several sources of organic waste. The results showed a high selectivity of black TiO2 toward glycolic acid, with the formation of glyoxylic acid being the rate-limiting step (glyoxylic acid is the two-electron intermediate). The highest Faradaic efficiency (FE) of 69.6% ± 8.3% was achieved at 10.2 mA cm−2 in 4 h of electrolysis using an H-type cell operated at room temperature, with 50.2% ± 3.8% of oxalic acid conversion (degradation kinetic constant k = 0.0042 ± 0.0001 min−1), 58.8% ± 7.0% of reaction yield and 1.2 ± 0.18 g L−1 of glycolic acid production. A theoretical model of black TiO2 coming from anatase TiO2 was implemented by introducing Ti3+ defects, which gave black TiO2 the theoretical capability to easily transform oxalic acid into glycolic acid as experimentally observed. The reaction mechanism was supported and described in detail by density functional theory calculations, which revealed that surface Ti3+ states were the main catalytic sites. This is the first time that a detailed step-by-step mechanism at the atomic level has been proposed for this electrocatalytic reaction, which represents a valuable contribution to the understanding of this process of high energy/environmental interest. This is also the first time that black TiO2 has been used as an electrocatalyst for this sustainable process.

Alloying effect-triggered electron polarization in PdCu metallene for simultaneous electrocatalytic upcycling of nitrate and polyethylene terephthalate to value-added chemicals

Electrocatalytic convert nitrate wastewater and discarded polyethylene terephthalate (PET) into high-value chemicals is an effective approach to addressing environmental pollution while generating economic benefits. To achieve this vision, herein, PdCu alloy metallene grown on Ni foam (PdCuene/NF) was synthesized via a one-step solvothermal method and directly used for anodic ethylene glycol oxidation reaction (EGOR), while an additional oxidation-electroreduction treatment was conducted to further convert it into reconstructed PdCuene/NF (r-PdCuene/NF) for cathodic nitrate reduction reaction (NO3RR). With the synergism of metallene array structure and alloying effect, the cathodic r-PdCuene/NF showed an enhanced nitrate-to-ammonia activity with a maximum Faradaic efficiency (FE) of 91.59 ± 2.79 %, while the anodic PdCuene/NF could effectively convert EG into glycolic acid (maximum FE: 92.12 % ± 0.26 %). The coupling of nitrate reduction with PET-derived EG oxidation based on these two materials allowed the simultaneous production of ammonia and glycolic acid with high FEs (>94 %).

Screening and fermentation of high-yield glycolic acid strains

Glycolic acid is an important chemical product widely used in various fields, including cosmetics, detergents, textiles, and more. Currently, microbial production of glycolic acid has disadvantages such as poor genetic stability, low yield, and high cost. Additionally, whole-cell catalytic production of glycolic acid typically requires the addition of relatively expensive sorbitol as a carbon source, which limits its industrial production. To develop an industrially applicable method for glycolic acid production, this study used ethylene glycol as a substrate to screen the glycolic acid-producing strains through whole-cell catalysis, obtaining a Rhodotorula sp. capable of producing glycolic acid. The strain was then subjected to UV mutagenesis and high throughput screening, and the positive mutant strain RMGly-20 was obtained. After optimization in shake flasks, the glycolic acid titer of RMGly-20 reached 17.8 g/L, a 10.1-fold increase compared to the original strain. Using glucose as the carbon source and employing a fed-batch culture in a 5 L fermenter, strain RMGly-20 produced 61.1 g/L of the glycolic acid. This achievement marks the preliminary breeding of a genetically stable glycolic acid-producing strain using a cheap carbon source, providing a new host for the biosynthesis of glycolic acid and promoting further progress toward industrial production.

Electrocatalytic Valorization of Nitrate and Polyester Plastic for Simultaneous Production of Ammonia and Glycolic Acid.

Electrochemical upcycling of nitrate and polyester plastic into valuable products is an ideal solution to realize the resource utilization. Here, the co-production of ammonia (NH3) and glycolic acid (GA) via electrochemical upcycling of nitrate and polyethylene terephthalate (PET) plastics over mesoporous Pd3Au film on Ni foam (mPd3Au/NF), which is synthesized by micelle-assisted replacement method, is proposed. The mPd3Au/NF with well-developed mesoporous structure provides abundant active sites and facilitated transfer channels and strong electronic effect. As such, the mPd3Au/NF exhibits high Faraday efficiencies of 97.28% and 95.32% at 0.9V for the formation of NH3 and GA, respectively. Theoretical results indicate that the synergistic effect of Pd and Au can optimize adsorption energy of key intermediates *NOH and *OCH2-CH2OH on active sites and increase bond energy of C─C band, thereby improving the activity and selectivity for the formation of NH3 and GA. This work proposes a promising strategy for the simultaneous conversation of nitrate and PET plastic into high-value NH3 and GA.

Visible‐Light Photoreforming of Biomass Derivatives through MBi2O4‐P25 Heterostructures: Study of the Influence of Metals (M = Cu, Ni, Zn, Co)

AbstractIn this work, MBi2O4‐P25 (M = Cu, Ni, Co, Zn) composites are successfully synthesized by a simple ball milling method by varying some parameters (rotation speed, rotation time, metal/TiO2 ratio) to optimize the preparation conditions. The noble metal‐free TiO2‐based photocatalysts are used to carry out the partial oxidation of glucose and glycerol with the simultaneous H2 production under simulated solar light irradiation. Starting from glucose, 2.6 mmol of H2 are obtained with a conversion of 34%, along with arabinose, formic acid and gluconic acid as main intermediates. By using glycerol, 3.2 mmol of H2 are produced, with 17% conversion and the production of dihydroxyacetone and glycolic acid. The composites exhibit higher activity than pure P25 and CuBi2O4 (CBO). The produced H2 amount is comparable to that reported in the literature by using Pt–TiO2 photocatalysts. This study offers a paradigm for the future design of bifunctional photocatalysts for simultaneous noble metal‐free H2 production and biomass valorization under environmentally friendly conditions with a possible scale up of the process.

Selective formation of glycolic acid by photocatalytic conversion of glycerol under sunlight with SnO2-based heterojunctions

Glycerol is a byproduct of biodiesel synthesis and is one of the most readily available platform molecules originating from biomass. Heterogeneous photocatalysis is a strategic approach, and reactions run under ambient conditions convert glycerol into industrially relevant molecules such as glycolic acid. The p-n type heterojunctions are useful photocatalysts because they can decrease the bandgaps and facilitate electron promotion between the bands of materials, thereby optimizing the formation of reactive oxygen species (ROS) and increasing reaction efficiencies. In this study, photocatalysts were synthesized via coprecipitation with a 5 % w/w mixture of Cu2+ and Ni2+ precursors, which produced the p-n heterojunctions SnO2/CuO-5 % and SnO2/NiO-5 %, respectively. Was observed an increase in the surface areas of the materials, which were ∼19 and 62 m2/g for SnO2/CuO-5 % and SnO2/NiO-5 %, respectively. The addition of metals to the heterojunctions enabled the use of solar light, due to the decrease of the bandgaps of the materials to 1.9 and 2.0 eV for SnO2/CuO-5 % and SnO2/NiO-5 %, respectively; these were lower than of SnO2 (2.54 eV). The photocatalytic activities of the heterojunctions were tested via glycerol oxidation, and after 4 h, the SnO2/CuO-5 % heterojunction exhibited the highest reaction efficiency (19 %), followed by 13 % and 11 % for SnO2/NiO-5 % and SnO2, respectively. The selectivities indicated the reaction pathway, in which glyceraldehyde and tartaric acid were intermediates for glycolic acid production; glycolic acid is the precursor to polyglycolic acid (PGA), for which production levels are increasing. The results of this study point to new technological pathways enabling responsible use of the resources present in nature and reuse of their byproducts, as with the conversion of glycerol to economically attractive molecules and contribute to a sustainable economy.

Integration of physical information and reaction mechanism data for surrogate prediction model and multi-objective optimization of glycolic acid production

With the continuous development of the chemical industry, the concept of advocating green development has become increasingly popular. Glycolic acid (GA), serving as the monomer for biodegradable plastic polyglycolic acid, plays a crucial role in combating plastic pollution and fostering an eco-friendly society. The selective oxidation of ethylene glycol (EG) to produce GA represents a novel green production technology. Controlling reaction parameters to achieve multi-objective optimization of product distribution and direct CO2 emissions is crucial for scaling up the process. With the advent of the big data era, the integration of the chemical industry with artificial intelligence to achieve engineering scale-up is an important trend. This study proposes a neural network model for production prediction and optimization. The model is trained using experimental data, reaction mechanism data, and physical information, enabling rapid prediction of GA production. After validating with 40% of experimental data and 16% of reaction mechanism data, the model's prediction error was within ±5%, and the linear correlation coefficient R2 between the predicted values and actual values was 0.998. Furthermore, this study integrated a multi-objective optimization algorithm based on the model, enabling surrogate optimization of reaction parameters during production. After optimization, the direct CO2 emissions were reduced by over 99% and overall greenhouse gas emissions were reduced by 4.6%. The research paradigm proposed in this research can offer guidance and technical support for the optimized operation of EG selective oxidation to GA.

Steering the Selective Production of Glycolic Acid by Electrocatalytic Oxidation of Ethylene Glycol with Nanoengineered PdBi-Based Heterodimers.

Heterodimers of metal nanocrystals (NCs) with tailored elemental distribution have emerged as promising candidates in the field of electrocatalysis, owing to their unique structures featuring heterogeneous interfaces with distinct components. Despite this, the rational synthesis of heterodimer NCs with similar elemental composition remains a formidable challenge, and their impact on electrocatalysis has remained largely elusive. In this study, Pd@Bi-PdBi heterodimer NCs are synthesized through an underpotential deposition (UPD)-directed growth pathway. In this pathway, the UPD of Bi promotes a Volmer-Weber growth mode, allowing for judicious modulation of core-satellite to heterodimer structures through careful control of supersaturation and growth kinetics. Significantly, the heterodimer NCs are employed in the electrocatalytic process of ethylene glycol (EG) with high activity and selectivity. Compared with pristine Pd octahedra and common PdBi alloy NC, the unique heterodimer structure of the Pd@Bi-PdBi heterodimer NCs endows them with the highest electrocatalytic performance of EG and the best selectivity (≈93%) in oxidizing EG to glycolic acid (GA). Taken together, this work not only heralds a new strategy for UPD-directed synthesis of bimetallic NCs, but also provides a new design paradigm for steering the selectivity of electrocatalysts.

Biotransformation of ethylene glycol by engineered Escherichia coli

There has been extensive research on the biological recycling of PET waste to address the issue of plastic waste pollution, with ethylene glycol (EG) being one of the main components recovered from this process. Therefore, finding ways to convert PET monomer EG into high-value products is crucial for effective PET waste recycling. In this study, we successfully engineered Escherichia coli to utilize EG and produce glycolic acid (GA), expecting to facilitate the biological recycling of PET waste. The engineered E. coli, able to utilize 10 g/L EG to produce 1.38 g/L GA within 96 h, was initially constructed. Subsequently, strategies based on overexpression of key enzymes and knock-out of the competing pathways are employed to enhance EG utilization along with GA biosynthesis. An engineered E. coli, characterized by the highest GA production titer and substrate conversion rate, was obtained. The GA titer increased to 5.1 g/L with a yield of 0.75 g/g EG, which is the highest level in the shake flake experiments. Transcriptional level analysis and metabolomic analysis were then conducted, revealing that overexpression of key enzymes and knock-out of the competing pathways improved the metabolic flow in the EG utilization. The improved metabolic flow also leads to accelerated synthesis and metabolism of amino acids.

Conversion of CO2 into Glycolic Acid: A Review of Main Steps and Future Challenges

Exploring the potential of utilizing CO2 for commercial purposes is a promising opportunity, especially in light of the growing research efforts towards CO2 capture, storage, and utilization as well as green H2 production. This review article delves into catalyst features and other technological aspects of a plausible process for the indirect conversion of CO2 into glycolic acid, which involves the following steps: CO2 capture, water electrolysis, CO2 hydrogenation to methanol, catalytic oxidation to formaldehyde, and formaldehyde carbonylation to glycolic acid. We adopt an industrial perspective to address this challenge effectively, thoroughly evaluating different processing alternatives with emphasis on the catalytic systems to optimize glycolic acid production performance.

Boosting the Production of Glycolic Acid from Formaldehyde Carbonylation via the Bifunctional PdO/ZSM-5 Catalyst

Boosting the Production of Glycolic Acid from Formaldehyde Carbonylation via the Bifunctional PdO/ZSM-5 Catalyst

Light-dependent metabolic shifts in the model diatom Thalassiosira pseudonana

Diatoms are major producers of carbon and energy in aquatic ecosystems, however their ability to rapidly and successfully acclimate to wide ranging irradiances is poorly understood at the biochemical level. We applied complementary transcriptomic and metabolomic approaches using the model centric diatom Thalassiosira pseudonana to understand mechanisms regulating cell acclimation and growth under high and low light intensities. The integration of these omics data revealed specific mechanisms that shifted carbon and energy fluxes in T. pseudonana depending on light-driven growth rate. To support a growth rate of >1 d−1 in high light, cells upregulated metabolic pathways involved in the production of long chain fatty acids, glycolic acid, and carbohydrates. Under low light, cells maintained a growth rate of ≤0.2 d−1 by conserving photosynthetic energy through upregulation of carbon retention pathways (e.g., gluconeogenesis, glyoxylate cycle). The few significant metabolites detected in low light acclimated cells were associated with light harvesting, energy storage, and signalling. In particular, our metabolite data revealed that eicosanoic acid, a metabolite commonly involved in cellular signalling, may poise light limited cells for fast metabolic remodelling with improving light conditions. The combined physiological, gene expression and metabolite profiling data revealed key metabolic switch points that underpin diatom success and could be leveraged in cell-based models for predictions and manipulations of cell growth or bio-production.

Biotransformation of ethylene glycol to glycolic acid by Yarrowia lipolytica: a route for poly(ethylene terephthalate) (PET) upcycling.

Biological recycling of PET waste has been extensively investigated recently to tackle plastic waste pollution, and ethylene glycol (EG) is one of the main building blocks recovered from this process. Wild-type Yarrowia lipolytica IMUFRJ 50682 can be used as biocatalyst for this purpose. Herein, we report its ability to perform oxidative biotransformation of EG into glycolic acid (GA): a higher value-added chemical with varied industrial applications. Maximum non-inhibitory concentration assay for EG cytotoxicity revealed that this yeast tolerates high concentrations (up to 2 M). Whole-cell biotransformation assays using resting yeast cells showed GA production uncoupled to cell growth metabolism, and 13 C nuclear magnetic resonance (NMR) analysis confirmed GA production. Moreover, higher agitation speed (450 versus 350 rpm) resulted in a 1.12-fold GA production improvement (from 352 to 429.5 mM) during Y. lipolytica cultivation in bioreactors after 72 h. GA was constantly accumulated in the medium, suggesting that this yeast may also share an incomplete oxidation pathway (i.e., it is not metabolized to carbon dioxide) as seen in acetic acid bacterial group. Additional assays using higher chain-length diols (1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol) revealed that C4 and C6 diols were more cytotoxic, suggesting that they underwent different pathways in the cells. We found that this yeast consumed extensively all these diols, however, 13 C NMR analysis from supernatant identified solely the presence of 4-hydroxybutanoic acid from 1,4-butanediol, along with GA from EG oxidation. Findings reported herein reveal a potential route for PET upcycling to a higher value-added product. This article is protected by copyright. All rights reserved.

A hybrid deep learning framework driven by data and reaction mechanism for predicting sustainable glycolic acid production performance

AbstractSelective oxidation at low temperatures without alkali of biomass is a promising and sustainable avenue to manufacture glycolic acid (GA), a biodegradable functional material to protect the environment. However, producing glycolic acid with high selectivity and yield using the traditional research and development approach is time‐consuming and labor‐intensive. To this context, a hybrid deep learning framework driven by data and reaction mechanisms for predicting GA production was proposed, considering the lack of related reaction mechanisms in the machine learning algorithms. The proposed hybrid deep learning framework involves the kinetic reaction mechanism, catalyst properties, and reaction conditions. Results showed that the fully connected residual network exhibited superior performance (average R2 = 0.98) for the prediction of conversion rate and product yields. Then, the multi‐objective optimization and experimental verification guided the research are carried out. The experimental verification is comparable to the modeling results, with errors of less than 4% for conversion rate and GA yields. The life cycle assessment further identifies that using the optimized operating parameters, the fossil energy demand and greenhouse emissions have decreased by 2.96% and 3.00%, respectively. This work provides new insight and strategy to accelerate the engineered selective oxidation for desired GA production.

Selective Production of Glycolic Acid from Cellulose Promoted by Acidic/Redox Polyoxometalates via Oxidative Hydrolysis

The direct conversion of cellulose to glycolic acid (GA) with a high yield of up to 75% is realized using acidic/redox polyoxometalates (POMs) as catalysts in a one-pot reaction. Analysis of the reaction pathway and mechanism for the three POMs H3PMo12O40 (H3PMo), H3PW12O40 (H3PW), and H5PMo10V2O40 (H5PMoV2) by density functional theory calculations and experiments shows that H3PMo is especially promising. Activation of O2 to •O2– and 1O2 via one-electron transfer assists the depolymerization process of cellulose by acidic/redox H3PMo. The reduced form [PMo10VIMo2VO39]5– plays a crucial role in GA production due to its high activity and ability to stabilize the intermediates of the retro-aldol reaction. H3PMo was furthermore complexed by the ionic liquid 1-(3-sulfonic group) propyl-3-methyl imidazolium (MIMPS), which enables easy recovery from the reaction solution due to temperature-responsive properties of the complexes. [MIMPS]H2PMo provides an outstanding GA selectivity of 61% under aerobic conditions and is comparable to the homogeneous H3PMo. Activity and selectivity to GA could be improved to 100 and 75%, respectively, by performing the reaction in the microwave at 190 °C for 2 min. The work deepens the insight on cellulosic biomass transformation over POMs by acidic/oxidative synergetic catalysis and contributes to the effort of designing highly active, selective, and multifunctional catalysts.

A switchable route for selective transformation of ethylene glycol to hydrogen and glycolic acid using a bifunctional ruthenium catalyst.

The developed bifunctional NNN-Ru complex features a high catalytic efficiency for the selective production of hydrogen and glycolic acid from ethylene glycol under mild reaction conditions, where a TON of 6395 was achieved. Tuning the reaction conditions afforded further dehydrogenation of the organic substrate with higher hydrogen production, and a higher TON of 25 225 was attained. The scale-up reaction yielded 1230 mL of pure hydrogen gas under the optimized reaction conditions. The role of the bifunctional catalyst was studied and mechanistic investigations were performed.

Concurrent production and purification of glycolic acid from mixed esters via selective hydrolysis reactions catalyzed and thermodynamically promoted by MgO

Methyl glycolate (MG) in the presence of methyl levulinate (MLE) was selectively converted into magnesium glycolate via MgO-mediated hydrolysis reactions under mild conditions. The conversion of MG reached 95.2% while that of MLE was 15.1%, with reaction selectivity of 100%. After facile isolation procedures, the magnesium glycolate was readily transformed into glycolic acid, monomer of biodegradable plastic, with recovery rate of 90.2%. The basic sites with medium strength on MgO dominated the catalytic activity. The precipitation of magnesium glycolate led to the shift of chemical equilibrium for MG hydrolysis. DFT calculation results showed that the energy barriers for MG hydrolysis were smaller than those for MLE hydrolysis by 46–47 kJ/mol. Both the shift of chemical equilibrium and lower energy barriers contributed to the much higher reactivity of MG compared to MLE. This paper sheds light on the selective hydrolysis of esters and complete hydrolysis of an ester.

Bismuth-Decorated Beta Zeolites Catalysts for Highly Selective Catalytic Oxidation of Cellulose to Biomass-Derived Glycolic Acid

Catalytic conversion of cellulose to liquid fuel and highly valuable platform chemicals remains a critical and challenging process. Here, bismuth-decorated β zeolite catalysts (Bi/β) were exploited for highly efficient hydrolysis and selective oxidation of cellulose to biomass-derived glycolic acid in an O2 atmosphere, which exhibited an exceptionally catalytic activity and high selectivity as well as excellent reusability. It was interestingly found that as high as 75.6% yield of glycolic acid over 2.3 wt% Bi/β was achieved from cellulose at 180 °C for 16 h, which was superior to previously reported catalysts. Experimental results combined with characterization revealed that the synergetic effect between oxidation active sites from Bi species and surface acidity on H-β together with appropriate total surface acidity significantly facilitated the chemoselectivity towards the production of glycolic acid in the direct, one-pot conversion of cellulose. This study will shed light on rationally designing Bi-based heterogeneous catalysts for sustainably generating glycolic acid from renewable biomass resources in the future.