Production Of Glycolic Acid Research Articles

Cost-practical of glycolic acid bioproduction by immobilized whole-cell catalysis accompanied with compressed oxygen supplied to enhance mass transfer

Bioprocess for Glycolic acid (GA) production from ethylene glycol by whole-cell catalysis of Gluconobacter oxydans is restrained by various biological impediments and high production costs. In this study, these limitations were subsided through the implementation of immobilized whole-cell bio-catalysis combined with increased oxygen supply. Results indicated that this strategy noticeably enhanced mass transfer efficiency, and prolonged cell life that significantly reduced the cost of biomass. Ultimately, with immobilized whole-cell catalysis in air-open and oxygen-open bioreactor, 41.3 and 66.9 g/L of GA was obtained within 48 h, with an increment of 62.0%. Additionally, in oxygen-compressed bioreactor, 63.3 g/L of GA was accumulated with the yield of 97.2%. Subsequently, 605.7 g of GA was produced after 10 rounds of recovery experiments. Although there was a slight decrease in GA production compared with pure-oxygen supply, production cost was reduced with limited oxygen supply. This strategy commendably demonstrated cost-practical bioprocess for GA production.

One-step continuous/semi-continuous whole-cell catalysis production of glycolic acid by a combining bioprocess with in-situ cell recycling and electrodialysis

Bioprocess for successive bio-production of glycolic acid (GA) from ethylene glycol (EG) using Gluconobacter oxydans is hindered by strong end-product inhibitory effect. Based on the model of compressed oxygen supplied-sealed stirred tank reactor (COS-SSTR), we developed a new system by attaching an ultrafiltration instrument and electrodialysis cell to in-situ separate GA, including conductivity meter to control automatic EG feeding. The combined bioprocess was therefore set up as compressed oxygen supplied cell catalysis-ultrafiltration-electrodialysis (COS-CUE). In comparison with the conventional resin and electrodialysis separation process, this device simplified the whole bioprocess. We realized the potential of combined bioprocess for producing GA without EG through continuous/semi-continuous ‘one-step’ process. Finally, 288.4 g GA was obtained at the yield of 96.5% and average productivity of 4.0 g/L/h in 72 h, with an increment of 148.8% and 20.9% in production compared with batch and cell-recycling fermentation.

Engineering Escherichia coli for glycolic acid production from D-xylose through the Dahms pathway and glyoxylate bypass.

Glycolic acid (GA) is an ⍺-hydroxy acid used in cosmetics, packaging, and medical industries due to its excellent properties, especially in its polymeric form. In this study, Escherichia coli was engineered to produce GA from D-xylose by linking the Dahms pathway, the glyoxylate bypass, and the partial reverse glyoxylate pathway (RGP). Initially, a GA-producing strain was constructed by disrupting the xylAB and glcD genes in the E. coli genome and overexpressing the xdh(Cc) from Caulobacter crescentus. This strain was further improved through modular optimization of the Dahms pathway and the glyoxylate bypass. Results for module 1 showed that the rate-limiting step of the Dahms pathway was the xylonate dehydratase reaction, and the overexpression of yagF was sufficient to overcome this bottleneck. Furthermore, the appropriate aldolase gene for module 1 was proven to be yagE. The results also show that overexpression of the lactaldehyde dehydrogenase gene, aldA, is needed to increase the GA production while the overexpression of glyoxylate reductase gene, ycdW, was only essential when the glyoxylate bypass was active. On the other hand, the module 2 enzymes AceA and AceK were vital in activating the glyoxylate bypass, while the RGP enzymes were dispensable. The final strain (GA19) produced 4.57g/L GA with a yield of 0.46g/g from D-xylose. So far, this is the highest value achieved for GA production in engineered E. coli through the Dahms pathway.

Production of ethylene glycol or glycolic acid from D-xylose in Saccharomyces cerevisiae.

The important platform chemicals ethylene glycol and glycolic acid were produced via the oxidative D-xylose pathway in the yeast Saccharomyces cerevisiae. The expression of genes encoding D-xylose dehydrogenase (XylB) and D-xylonate dehydratase (XylD) from Caulobacter crescentus and YagE or YjhH aldolase and aldehyde dehydrogenase AldA from Escherichia coli enabled glycolic acid production from D-xylose up to 150mg/L. In strains expressing only xylB and xylD, 29mg/L 2-keto-3-deoxyxylonic acid [(S)-4,5-dihydroxy-2-oxopentanoic acid] (2K3DXA) was produced and D-xylonic acid accumulated to ca. 9g/L. A significant amount of D-xylonic acid (ca. 14%) was converted to 3-deoxypentonic acid (3DPA), and also, 3,4-dihydroxybutyric acid was formed. 2K3DXA was further converted to glycolaldehyde when genes encoding by either YagE or YjhH aldolase from E. coli were expressed. Reduction of glycolaldehyde to ethylene glycol by an endogenous aldo-keto reductase activity resulted further in accumulation of ethylene glycol of 14mg/L. The possibility of simultaneous production of lactic and glycolic acids was evaluated by expression of gene encoding lactate dehydrogenase ldhL from Lactobacillus helveticus together with aldA. Interestingly, this increased the accumulation of glycolic acid to 1g/L. The D-xylonate dehydratase activity in yeast was notably low, possibly due to inefficient Fe-S cluster synthesis in the yeast cytosol, and leading to D-xylonic acid accumulation. The dehydratase activity was significantly improved by targeting its expression to mitochondria or by altering the Fe-S cluster metabolism of the cells with FRA2 deletion.

Kinetic modelling of the glycerol oxidation in the liquid phase: comparison of Pt, Au and Ag AS active phases

AbstractBACKGROUNDUnlike Pt and Au, Ag has recently been reported to be an active catalyst for the synthesis of glycolic acid from the liquid phase oxidation of glycerol (GLY). In order to provide comparative information about the kinetics of this reaction using Pt, Au or Ag, a kinetic model was derived for each catalyst (Ag/, Pt/ and Au/Al2O3), using the experimental results obtained at different temperatures.RESULTSA power‐law kinetic model was proposed for each catalyst, which included the Khang–Levenspiel model to evaluate potential catalyst deactivation. All three kinetic models predicted well the experimental concentrations. Pt/ and Au/Al2O3 showed higher kinetic rate constants, the highest being that of the production of glyceric acid. The lower the metal particle size, the higher the kinetic rate constant of the production of glyceric acid was. Deactivation parameters played an important role in the model of Pt/Al2O3, so that Au/ and Ag/Al2O3 seemed to be more resistant to deactivation.CONCLUSIONSThis work reports the first kinetic model for the oxidation of GLY using an Ag‐based catalyst. It showed a noticeable kinetic rate constant for the production of glycolic acid. The activation energies obtained were in the range 48–97 kJ mol−1. © 2017 Society of Chemical Industry

Determination of glycolic acid in natural seawater by liquid chromatography coupled with triple quadrupole mass spectrometry

AbstractGlycolic acid, which is produced during photorespiration, is one of the major components of dissolved organic matter released by phytoplankton, comprising up to 40% of their daily primary productivity. However, the sensitivity of existing methods does not allow for accurate measurement of glycolic acid levels in oligotrophic seawater. In this study, we present a straightforward, robust, and sensitive liquid chromatography‐mass spectrometry (LC‐MS) method to quantify glycolic acid in natural seawater following liquid‐liquid extraction, requiring only a small sample size (25 mL seawater). The method has a highly sensitive detection limit of 9 nM, at least fivefold lower than existing methods. This approach was successfully applied to the analysis of seawater samples collected from both eutrophic and oligotrophic marine environments. The results showed that glycolic acid concentrations in natural seawater are positively correlated with chlorophyll a concentrations, indicating that phytoplankton contribute significantly to glycolic acid production in marine environments. As glycolic acid is an important carbon and energy source for marine bacteria, the method developed within this study allows further investigation into the rates of its release and uptake by phytoplankton and heterotrophic bacteria, respectively, as well as the role it plays in phytoplankton–bacteria interactions.

Direct Power Charge and Discharge Using the Glycolic Acid/Oxalic Acid Redox Couple toward Carbon-Neutral Energy Circulation

We demonstrated an electric power circulation method that does not emit CO2 and is based on the glycolic acid (GC)/oxalic acid (OX) redox couple. Electric power charge in GC was achieved through OX electro-reduction with high selectivity (>98%) using purely anatase-type TiO2 spheres in the potential region of -0.5 to -0.7 V vs. RHE at 50 ºC. We also realized GC production via the combination of electrochemical OX reduction and electro-oxidation of water with the help of renewable light energy for the first time. Furthermore, we succeeded in power generation via the selective electro-oxidation of GC to OX without CO2 emission. These results are the first experimental proof of the carbon-neutral power circulation involving an alcohol/carboxylic acid redox couple.

The synthetic xylulose-1 phosphate pathway increases production of glycolic acid from xylose-rich sugar mixtures.

BackgroundGlycolic acid (GA) is a two-carbon hydroxyacid with applications in the cosmetic, textile, and medical industry. Microbial GA production from all sugars can be achieved by engineering the natural glyoxylate shunt. The synthetic (d)-xylulose-1 phosphate (X1P) pathway provides a complementary route to produce GA from (d)-xylose. The simultaneous operation of the X1P and glyoxylate pathways increases the theoretical GA yield from xylose by 20 %, which may strongly improve GA production from hemicellulosic hydrolysates.ResultsWe herein describe the construction of an E. coli strain that produces GA via the glyoxylate pathway at a yield of 0.31 , 0.29 , and 0.37 g/g from glucose, xylose, or a mixture of glucose and xylose (mass ratio: 33:66 %), respectively. When the X1P pathway operates in addition to the glyoxylate pathway, the GA yields on the three substrates are, respectively, 0.39 , 0.43 , and 0.47 g/g. Upon constitutive expression of the sugar permease GalP, the GA yield of the strain which simultaneously operates the glyoxylate and X1P pathways further increases to 0.63 g/g when growing on the glucose/xylose mixture. Under these conditions, the GA yield on the xylose fraction of the sugar mixture reaches 0.75 g/g, which is the highest yield reported to date.ConclusionsThese results demonstrate that the synthetic X1P pathway has a very strong potential to improve GA production from xylose-rich hemicellulosic hydrolysates.

Enhancement of cell growth and glycolic acid production by overexpression of membrane-bound alcohol dehydrogenase in Gluconobacter oxydans DSM 2003

Membrane-bound alcohol dehydrogenase (mADH) was overexpressed in Gluconobacter oxydans DSM 2003, and the effects on cell growth and glycolic acid production were investigated. The transcription levels of two terminal ubiquinol oxidases (bo3 and bd) in the respiratory chain of the engineered strain G. oxydans-adhABS were up-regulated by 13.4- and 3.8-fold, respectively, which effectively enhanced the oxygen uptake rate, resulting in higher resistance to acid. The cell biomass of G. oxydans-adhABS could increase by 26%–33% when cultivated in a 7L bioreactor. The activities of other major membrane-bound dehydrogenases were also increased to some extent, particularly membrane-bound aldehyde dehydrogenase (mALDH), which is involved in the catalytic oxidation of aldehydes to the corresponding acids and was 1.26-fold higher. Relying on the advantages of the above, G. oxydans-adhABS could produce 73.3gl−1 glycolic acid after 45h of bioconversion with resting cells, with a molar yield 93.5% and a space-time yield of 1.63gl−1h−1. Glycolic acid production could be further improved by fed-batch fermentation. After 45h of culture, 113.8gl−1 glycolic acid was accumulated, with a molar yield of 92.9% and a space-time yield of 2.53gl−1h−1, which is the highest reported glycolic acid yield to date.

Simultaneous production of glycolic acid via the glyoxylate shunt and the synthetic (d)-xylulose-1 phosphate pathway increases product yield

Glycolic acid (GA) is an alpha-hydroxy acid with a wide range of chemical and pharmaceutical applications...

Hydrogenation of oxalic acid using light-assisted water electrolysis for the production of an alcoholic compound

We demonstrate the production of glycolic acid, an industrially important alcoholic compound, via the electrochemical reduction of oxalic acid, which is procurable from biomass, and electro-oxidation of water with the help of renewable light energy for the first time.

Metabolic engineering of E. coli for efficient production of glycolic acid from glucose

Glycolic acid is the smallest member of the α-hydroxy acid family. In order to produce glycolate from glucose via the glyoxylate shunt stably, one malate synthase gene aceB in Escherichia coli BW25113 was deleted by homologous recombination; another malate synthase gene glcB was then replaced by a DNA cassette WAK harboring isocitrate lyase gene (aceA), glyoxylate reductase gene (ycdW) and isocitrate dehydrogenase kinase/phosphatase gene (aceK). The above three genes were over-expressed in the chromosome of E. coli EYX-1WAK. This strain was then transferred 20 times on M9 medium to have a mutant strain: EYX-2 with a significantly improved growth rate. The glycolate yields of EYX-2 in the shaken flasks and the 5-L bioreactor using batch fermentation strategy under 2vvm aeration and 800rpm stirring speed were 0.33g/g-glucose and 0.48g/g-glucose, respectively. The fed-batch fermentation of EYX-2 on 120g/L glucose had the highest titer of 56.44g/L with 0.52g/g-glucose yield in 120h, and this is the highest reported glycolate yield ever.

Production of glycolic acid from glycerol using novel fine-disperse platinum catalysts

Using extractive-pyrolytic method fine-disperse Pt containing composites were synthesized and tested in catalytic glycerol oxidation. Catalyst activity and selectivity to glycolic acid was determined oxidizing glycerol in mild conditions. It was concluded that only iron containing platinum catalysts were selective to glycolic acid. Selectivity to glycolic acid reached 53-60% with glycerol conversion 12-56%.

A Novel Microbial Aldehyde Oxidase Applicable to Production of Useful Raw Materials, Glycolic Acid and Glyoxylic Acid, from Ethylene Glycol

A Novel Microbial Aldehyde Oxidase Applicable to Production of Useful Raw Materials, Glycolic Acid and Glyoxylic Acid, from Ethylene Glycol

Enhanced bioconversion of ethylene glycol to glycolic acid by a newly isolated Burkholderia sp. EG13.

Burkholderia sp. EG13 with high ethylene glycol-oxidizing activity was isolated from soil, which could be used for the synthesis of glycolic acid from the oxidation of ethylene glycol. Using the resting cells of Burkholderia sp. EG13 as biocatalysts, the optimum reaction temperature and pH were 30°C and 6.0, respectively. After 24h of biotransformation, the yield of glycolic acid from 200mM ethylene glycol was 98.8%. Furthermore, an integrated bioprocess for the production of glycolic acid which involved in situ product removal (ISPR) was investigated. Using fed-batch method with ISPR, a total of 793mM glycolic acid has been accumulated in the reaction mixture after the 4th feed.

A continuous process for glyoxal valorisation using tailored Lewis-acid zeolite catalysts

The aqueous-phase heterogeneously catalysed isomerisation of bio-oil derived glyoxal is herein introduced as a novel route for the sustainable production of glycolic acid. While commercial ultra-stable Y zeolites displayed only moderate performance, their evaluation enabled us to highlight the crucial role of Lewis acidity in the reaction. Gallium incorporation into these zeolites boosted the glycolic acid yield, although the best catalytic results were obtained over tin-containing MFI-type zeolites, reaching 91% yield of the desired product at full conversion. These materials comprised hydrothermally-synthesised Sn-MFI as well as a novel catalyst obtained by the introduction of tin into silicalite-1 by means of a simpler and more scalable method, i.e. alkaline-assisted metallation. In-depth spectroscopic characterisation of these systems uncovered a substantial similarity of the tin centres obtained by the top-down and bottom-up synthetic approaches. NMR spectroscopic studies gave evidence that the reaction follows a 1,2-hydride shift mechanism solely catalysed by Lewis-acid sites. The Sn-MFI analogue could be reused in 5 cycles without the need for intermediate calcination, did not evidence any tin leaching, and demonstrated suitability for utilisation under continuous-flow operation. The tin-based zeolites exhibited remarkable performance also in alcoholic solvents, leading to the one-pot production of relevant alkyl glycolates.

Catalytic Biofilms on Structured Packing for the Production of Glycolic Acid

While structured packing modules are known to be efficient for surface wetting and gas-liquid exchange in abiotic surface catalysis, this model study explores structured packing as a growth surface for catalytic biofilms. Microbial biofilms have been proposed as self-immobilized and self-regenerating catalysts for the production of chemicals. A concern is that the complex and dynamic nature of biofilms may cause fluctuations in their catalytic performance over time or may affect process reproducibility. An aerated continuous trickle-bed biofilm reactor system was designed with a 3 L structured packing, liquid recycling and pH control. Pseudomonas diminuta established a biofilm on the stainless steel structured packing with a specific surface area of 500 m2 m-3 and catalyzed the oxidation of ethylene glycol to glycolic acid for over two months of continuous operation. A steady-state productivity of up to 1.6 gl-1h-1 was achieved at a dilution rate of 0.33 h-1. Process reproducibility between three independent runs was excellent, despite process interruptions and activity variations in cultures grown from biofilm effluent cells. The results demonstrate the robustness of a catalytic biofilm on structured packing, despite its dynamic nature. Implementation is recommended for whole-cell processes that require efficient gas-liquid exchange, catalyst retention for continuous operation, or improved catalyst stability.

Glycolic acid production in the engineered yeasts Saccharomyces cerevisiae and Kluyveromyces lactis

BackgroundGlycolic acid is a C2 hydroxy acid that is a widely used chemical compound. It can be polymerised to produce biodegradable polymers with excellent gas barrier properties. Currently, glycolic acid is produced in a chemical process using fossil resources and toxic chemicals. Biotechnological production of glycolic acid using renewable resources is a desirable alternative.ResultsThe yeasts Saccharomyces cerevisiae and Kluyveromyces lactis are suitable organisms for glycolic acid production since they are acid tolerant and can grow in the presence of up to 50 g l-1 glycolic acid. We engineered S. cerevisiae and K. lactis for glycolic acid production using the reactions of the glyoxylate cycle to produce glyoxylic acid and then reducing it to glycolic acid. The expression of a high affinity glyoxylate reductase alone already led to glycolic acid production. The production was further improved by deleting genes encoding malate synthase and the cytosolic form of isocitrate dehydrogenase. The engineered S. cerevisiae strain produced up to about 1 g l-1 of glycolic acid in a medium containing d-xylose and ethanol. Similar modifications in K. lactis resulted in a much higher glycolic acid titer. In a bioreactor cultivation with d-xylose and ethanol up to 15 g l-1 of glycolic acid was obtained.ConclusionsThis is the first demonstration of engineering yeast to produce glycolic acid. Prior to this work glycolic acid production through the glyoxylate cycle has only been reported in bacteria. The benefit of a yeast host is the possibility for glycolic acid production also at low pH, which was demonstrated in flask cultivations. Production of glycolic acid was first shown in S. cerevisiae. To test whether a Crabtree negative yeast would be better suited for glycolic acid production we engineered K. lactis in the same way and demonstrated it to be a better host for glycolic acid production.

Production of glycolic acid by chemolithotrophic iron- and sulfur-oxidizing bacteria and its role in delineating and sustaining acidophilic sulfide mineral-oxidizing consortia.

Glycolic acid was detected as an exudate in actively growing cultures of three chemolithotrophic acidophiles that are important in biomining operations, Leptospirillum ferriphilum, Acidithiobacillus (At.) ferrooxidans, and At. caldus. Although similar concentrations of glycolic acid were found in all cases, the concentrations corresponded to ca. 24% of the total dissolved organic carbon (DOC) in cultures of L. ferriphilum but only ca. 5% of the total DOC in cultures of the two Acidithiobacillus spp. Rapid acidification (to pH 1.0) of the culture medium of At. caldus resulted in a large increase in the level of DOC, although the concentration of glycolic acid did not change in proportion. The archaeon Ferroplasma acidiphilum grew in the cell-free spent medium of At. caldus; glycolic acid was not metabolized, although other unidentified compounds in the DOC pool were metabolized. Glycolic acid exhibited levels of toxicity with 21 strains of acidophiles screened similar to those of acetic acid. The most sensitive species were chemolithotrophs (L. ferriphilum and At. ferrivorans), while the most tolerant species were chemoorganotrophs (Acidocella, Acidobacterium, and Ferroplasma species), and the ability to metabolize glycolic acid appeared to be restricted (among acidophiles) to Firmicutes (chiefly Sulfobacillus spp.). Results of this study help explain why Sulfobacillus spp. rather than other acidophiles are the main organic carbon-degrading bacteria in continuously fed stirred tanks used to bioprocess sulfide mineral concentrates and also why temporary cessation of pH control in these systems, resulting in rapid acidification, often results in a plume of the archaeon Ferroplasma.

Adsorptive bioconversion of ethylene glycol to glycolic acid by Gluconobacter oxydans DSM 2003

An integrated bioprocess for the production of glycolic acid from ethylene glycol with Gluconobacter oxydans DSM 2003 and in situ product removal were investigated. A slight substrate inhibition was observed as substrate concentration was above 20 g/l and the product inhibition was much stronger. Bioconversion of glycolic acid is an end-product-inhibited reaction. In order to increase the productivity of glycolic acid and reduce the end-product inhibition of bioconversion, an adsorptive bioconversion for glycolic acid production from ethylene glycol catalyzed by resting cells of G. oxydans DSM 2003, was developed by using anion exchange resin D315 as the adsorbent for selective removal of glycolic acid from the reaction mixture. This approach allowed the yield of glycolic acid to be increased to 93.2 g/l, compared to 74.5 g/l obtained from a conventional fed-batch mode.