• 14 JUIL 2017

    Wheat and Sugar Beet Coproducts for the Bioproduction of 3-Hydroxypropionic Acid by Lactobacillus reuteri DSM17938

    An experimental design based on Response Surface Methodology (RSM) was used for the formulation of a growth medium based on sugar beet and wheat processing coproducts adapted to the cultivation of Lactobacillus reuteri (L. reuteri) DSM17938. The strain was cultivated on 30 different media varying by the proportions of sugar beet and wheat processing coproducts, and the concentration of yeast extract, tween 80 and vitamin B12. The media were used in a two-step process consisting of L. reuteri cultivation followed by the bioconversion of glycerol into 3-hydroxypropionic acid by resting cells. The efficiency of the formulations was evaluated according to the maximal optical density at the end of the growth phase (ΔOD620nm) and the ability of the resting cells to convert glycerol into 3-hydroxypropionic acid, a platform molecule of interest for the plastic industry. De Man, Rogosa, and Sharpe medium (MRS), commonly used for the cultivation of lactic bacteria, was used as the control medium. The optimized formulation allowed increasing the 3-HP production.
  • 14 JUIL 2017

    Elucidating nuclear motions in a plant sunscreen during photoisomerization, through solvent viscosity effects

    We explore the effects of solvent viscosity on trans-cis photoisomerization of sinapoyl malate, which is utilized as a sunscreen molecule in plants. Our results demonstrate that viscosity has a signifcant effect on the timescale for isomerization, providing insight into the nuclear motions involved. The ramifications of these finding are discussed with reference to sinapoyl malate’s in vivo photoprotection properties.
  • 14 JUIL 2017

    Lignocellulosic fibers: a critical review of the extrusion process for enhancement of the properties of natural fibers composites

    Natural fiber composites have various applications, since they can bring interesting mechanical and sustainability properties. Extrusion with a single- or twin-screw is the main industrial process to incorporate lignocellulosic fibers into polymers. In this review, the origin and preparation of lignocellulosic fibers are first presented, before discussing the composite processing, with a particular emphasis on the impact of process conditions on the composites final properties that is highly related to the final application. A broad panel of composites reinforced with lignocellulosic fibers is reviewed along with their polymeric matrix, lignocellulosic fiber type and pretreatments, and extrusion process conditions. Finally, the most critical extrusion process parameters (screw profile, speed and temperature) are also examined in order to determine some guidelines to optimize lignocellulosic fiber composites preparation.
  • 06 JUIN 2017

    A novel and integrative process: From enzymatic fractionation of wheat bran with a hemicellulasic cocktail to the recovery of ferulic acid by weak anion exchange resin

    An integrated and eco-friendly process including enzymatic hydrolysis with a hemicellulasic cocktail and a chromatographic purification step was developed to obtain ferulic acid from wheat bran. Thermobacillus xylanilyticus, a thermophilic and hemicellulolytic bacterium, was able to produce enzymatic cocktails containing xylanase, xylosidase, arabinosidase and esterase activities. The cocktails produced were used to deconstruct destarched wheat bran, allowing the release of 6%, 20% and 37% (w/w) of monomeric arabinose, xylose and ferulic acid, respectively. A weak anionic resin under free-base form was proved successful to separate the carbohydrate fraction from the ferulate one after acidification. Ferulate was recovered at high concentration (15 g/L) during regeneration of the resin. This non-optimized purification step allowed recovering 67% of ferulic acid fixed on the resin. Global recovery of ferulic acid contained in wheat bran after both enzymatic fractionation and purification stages reached 21.8%.
  • 06 JUIN 2017

    Conversion of Glycerol to 3-Hydroxypropanoic Acid by Genetically Engineered Bacillus subtilis

    3-Hydroxypropanoic acid (3-HP) is an important biomass-derivable platform chemical that can be converted into a number of industrially relevant compounds. There have been several attempts to produce 3-HP from renewable sources in cell factories, focusing mainly on Escherichia coli, Klebsiella pneumoniae, and Saccharomyces cerevisiae. Despite the significant progress made in this field, commercially exploitable large-scale production of 3-HP in microbial strains has still not been achieved. In this study, we investigated the potential of Bacillus subtilis as a microbial platform for bioconversion of glycerol into 3-HP. Our recombinant B. subtilis strains overexpress the two-step heterologous pathway containing glycerol dehydratase and aldehyde dehydrogenase from K. pneumoniae. Genetic engineering, driven by in silico optimization, and optimization of cultivation conditions resulted in a 3-HP titer of 10 g/L, in a standard batch cultivation. Our findings provide the first report of successful introduction of the biosynthetic pathway for conversion of glycerol into 3-HP in B. subtilis. With this relatively high titer in batch, and the robustness of B. subtilis in high density fermentation conditions, we expect that our production strains may constitute a solid basis for commercial production of 3-HP.
  • 22 MARS 2017

    From Bench Scale to kilolab Production of Renewable Ferulic Acid-based Bisphenols: Optimisation and Evaluation of Different Purification Approaches Towards a Technical Feasibility and Process Environmental Sustainability

    In earlier authors work, a new class of non-toxic and renewable bisphenols able to substitute bisphenol A and exhibiting potent antioxidant and antiradical activities has been prepared from ferulic acid through a chemoenzymatic pathways at bench scale. Scaling-up a process is not always trivial and straightforward. Technical feasibility of synthesis and overall process yield must be assessed. All decisions should be justified regarding technical constraints and environmental sustainability. This work is focused on the kilolab production of bis-O-dihydroferuloyl 1,4-butanediol (BDF), one of these very promising renewable bisphenols. Recrystallization and organic diananofiltration in a single stage (SSD) and two stages (TSD) were compared taking into account the previous considerations. As result, the synthesis and purification of BDF by recrystallization were successfully scaled-up at kilolab scale, being obtained a significant improvement in the overall yield (from 63% at labscale to 84% at kilolab scale) for a purity grade of 95%. To assess the organic diananofiltration as an alternative purification method, a set of 6 commercial organic solvent resistant membranes were evaluated. Starting from a solution (1 g/L) containing 80%(w/w) of BDF and 20% (w/w) of an excess reagent (ethyl dihydroferulate, EtDFe), GMT-oNF1 membrane showed to be able to discriminate them. A two-stage membrane diafiltration (TSD) in cascade was proposed, being observed a drastic increase in the product yield (from 77% in a single stage to 95%) without compromising its final purity (95%). Since solvent recycling has a significant impact on the process sustainability, a nanofiltration step for solvent recovery was assessed, . 90% of the solvent was recovered with a level of impurities lower than 1%. Recrystallization and all filtration-based processes were compared in terms of green metrics such as mass and solvent intensity and energy consumption. Results showed that only the integration of solvent recycling in filtration-based processes and the use of a concentrated starting solution (150 g/L instead of 1 g/L) may lead to similar magnitude values observed for recrystallization. Thus, even being a less energetic intensive process (4-fold), the TSD is still a solvent intensive process (3-fold), which is inevitably reflected in a higher environmental footprint (evaluated by LCA).
  • 22 MARS 2017

    Towards an extractive bioconversion of 3-hydroxypropionic acid: Study of inhibition phenomena

    3-hydroxypropionic acid (3-HP) microbial synthesis through glycerol bioconversion by Lactobacillus reuteri is at the moment characterized by too low performances to consider production at industrial scale. To avoid its toxic accumulation in the medium and to recover this molecule of interest, 3-HP in situ reactive extraction from bioconversion broth was investigated using a hollow fiber membrane contactor (HFMC) in order to intensify its production. The so-called integrated system was compared with the conventional bioconversion system. The impact of the extractive bioconversion on the overall production performance and on cell physiological state was studied. Results underlined drastic inhibitory effects on the producing bacteria, especially under extractive bioconversion conditions despite the use of a HFMC supposed to avoid direct contact between organic phase and bacteria. Indeed, the extractant phase components (trioctylamine in n-decanol) were found to be toxic for the cells (due to solubility and by direct contact). These phenomena were increased by the presence of 3-hydroxypropionaldehyde (3-HPA) and 3-HP produced during glycerol bioconversion. These cumulative effects induced a complete loss of the cell membrane integrity and esterase activity after 1.5 h of extractive bioconversion. When the bioconversion was conducted alone, the bacterial inhibition was lower, as around 50% of L. reuteri cells remained active with unaltered membrane after 3 h. Hypotheses concerning the mechanisms of action of the observed inhibitions were proposed and discussed. This work highlighted the importance of performing such an integrative approach to address specific questions prior to the optimization of the whole process.
  • 16 FEV 2017

    New insights in reactive extraction mechanisms of organic acids: An experimental approach for 3-hydroxypropionic acid extraction with tri-n-octylamine

    A detailed study of 3-hydroxypropionic acid (3-HP) reactive extraction with tri-n-octylamine (TOA) is proposed for the first time. It aims at uncovering some solvent-solutes interactions and providing global mechanisms to better understand and design the reactive liquid-liquid extraction of 3-HP in a biotechnological process. Eleven solvents of similar molecular sizes and several chemical types (alcohols, esters and alkanes) were investigated to understand their role on the extraction ability. Alcohols were found to be the best solvents thanks to their H-bond donor characteristic and water loading that allowed good solvation of the acid-amine complexes. Further investigations were then undertaken, for n-decanol and oleyl alcohol as solvents, varying acid (0.0028 – 0.56 mol/L corresponding to 0.25 – 50 g/L) and amine (0 – 2.3 mol/L corresponding to 0 – 100% v/v) concentrations. At 0.011 mol/L (1 g/L) of 3-HP, maximum extraction yields of 77% for n-decanol and 51% for oleyl alcohol were found for 0.46 mol/L TOA (20% v/v). The initial TOA purity proved to have a major impact on the extraction yield at low initial acid concentration ( < 0.1 mol/L = 10 g/L). Impurities from the TOA manufacturing process were identified as n-octylamine and di-n-octylamine and quantified in the aqueous phase after extraction. Their major effect on the extraction yield has been assessed (up to 86% decrease).
  • 16 FEV 2017

    Ultrafast Barrierless Photoisomerization and Strong UV Absorption of Photoproducts in Plant Sunscreens

    We study the photoprotectivemechanisms of sinapoyl malate and sinapic acid in aqueous solution by utilizing femtosecond transient absorption spectroscopy and time-dependent density functional theory.We find that excitedππ* states of the two molecules relax to the ground states via a barrierless trans-cis photoisomerizationin a few tens of picoseconds. The formation of cis-photoproducts largely reduces the efficacy of sinapic acid as a sunscreen. In contrast,the efficacy ofthe plant sunscreen sinapoyl malate is affected slightly due to the strong UVabsorption of its cis isomer.
  • 18 JAN 2017

    Syringaresinol: a renewable and safer alternative to Bisphenol A for epoxy-amine resins

    A renewable bis-epoxy, SYR-EPO, has been prepared from syringaresinol, a naturally occurring bisphenol deriving from sinapic acid, using a chemo-enzymatic synthetic pathway. Estrogenic activity test revealed no endocrine disruption for syringaresinol. Its glycidylation afforded bis-epoxy SYR-EPO with excellent yield and purity. This biobased safer epoxy precursor was then cured with conventional and renewable diamines for the preparation of epoxy-amine resins. The resulting thermosets were thermally and mechanically characterized (TGA, DSC and DMA). Thermal analyses of these new resins showed excellent thermal stabilities (Td5% = 279-309 °C) and Tg ranging from 73 to 126 °C, almost reaching the properties of those obtained with DiGlycidylEther of Bisphenol A (DGEBA), extensively used in polymer industry (Td5% = 319 °C and Tg = 150 °C for DGEBA-IPDA resins). Degradation studies in NaOH and HCl aqueous solutions also highlighted the robustness of the syringaresinol-based resins, similar to bisphenol A (BPA). All these results undoubtedly confirmed the potential of syringaresinol as a greener and safer substitute to BPA.
  • 31 DEC 2016

    Exploring the microstructure of natural fibre composites by confocal Raman imaging and image analysis

    We describe a combination of Confocal Raman Imaging (CRI) and quantitative image analysis to characterise biocomposite material microstructures. Both techniques offer lateral resolutions close to 1.3 μm and axial resolution of 13 μm, while simplifying sample preparation to hand-cutting without any surface preparation. Extruded and injected polycaprolactone/hemp fibre composites were used as demonstration biocomposites. A green macrobisphenol additive (bis-O-dihydroferuloyl-1,4-butanediol) was also used as a chemical probe to characterise the dispersion efficiency of additives, with a detection threshold of 2.3 wt% above which very local heterogeneity can be determined by this technique. CRI provided microstructure information for the entire binary structure formed by the fibre network. The fibre dispersion and orientation depend on their location in the matrix, and the specific surface of the fibres increases with the fibre content as aggregates start to develop. The technique also highlighted a possible core-skin effect in the injected composite
  • 31 DEC 2016

    Chemo-enzymatic synthesis and characterization of renewable thermoplastic and thermoset isocyanate-free poly(hydroxy)urethanes from ferulic acid derivatives

    This study presents the syntheses and characterization of renewable non-isocyanate polyurethanes from a new family of aromatic C5-cyclocarbonate precursors with different functionalities obtained from non-toxic ferulic acid derivatives by glycidylation and carbonation under high carbon dioxide pressure. Depending on the functionality, linear NIPU chains (thermoplastics) or cross-linked NIPU networks (thermosets) have been obtained. The thermoplastics NIPU molar masses were determined using SEC and 1H-NMR. The thermal and thermo-mechanical properties of the NIPUs were assessed by DSC, DMA (for thermosets), and TGA to determine the influence of the NIPU chemical structure on its properties. The range of Tg obtained (17 - 72 °C) was efficiently correlated with the degree of freedom and the molar mass of the NIPU repeat unit.
  • 31 DEC 2016

    Ferulic acid-based renewable esters and amides-containing epoxy thermosets from wheat bran and beetroot pulp: Chemo-enzymatic synthesis and thermo-mechanical properties characterization

    In this study, ferulic acid – a natural phenolic acid present in bagasse, wheat and rice brans, and beetroot pulp – was used as renewable starting material to prepare new biobased epoxy precursors. This biobased building block was first esterified then reduced to provide ethyl dihydroferulate which was then trans-esterified/amidified with biobased diols, triol and diamines. Immobilized Candida antarctica (aka CAL-B or Novozyme 435®) was used to perform the solvent-free-transesterification/amidation under mild conditions. The phenolic architectures synthesized were then glycidylated using a TEBAC-mediated procedure to afford four biobased epoxy precursors – with various linker structures between the ferulic units – which were then cured with conventionnal and biobased diamine curing agents. The thermal and thermomechanical properties of the thermosets prepared were assessed by TGA, DSC and DMA to highlight the influence of the linker configuration (aliphatic vs cycloaliphatic), that of the epoxy functionality (di vs tri), and that of the nature of the function used for coupling ferulic units (ester vs amide) on the thermosets properties. Analyses of these thermosets revealed glass transition temperatures ranging from 32 to 85 °C and high thermal stabilities around 300 °C. The mechanical behavior of the biobased thermosets proved equivalent to that of the DGEBA-IPDA reference sytem at low temperatures (up to 40–100 °C depending on the epoxy precursor and diamine).
  • 13 OCT 2016

    Optimization of the Laccase-Catalyzed Synthesis of (±)-Syringaresinol and Study of its Thermal and Antiradical Activities

    We report herein an optimized biocatalytic oxidative process for the synthesis of syringaresinol from sinapyl alcohol at a multigram scale (93% yield) in very high yield. Syringaresinol thereby obtained is of sufficient chemical purity and exhibits good thermal and antiradical activities to be used without further purification in many applications related to polymer synthesis as an alternative to bisphenol A. Different mechanistic pathways were discussed to better understand the impact of reaction conditions on the type of linkage formed during the oxidative process. Antiradical activity (DPPH analysis) and thermal properties of syringaresinol are also discussed.
  • 08 SEP 2016

    Ferulic acid-based bis/trisphenols as renewable antioxidants for polypropylene and poly(butylene succinate)

    Green chemistry principles recommend the use of renewable feedstocks and biocatalysis to decrease environmental impact of chemicals manufacturing. In this scope, three ferulic acid based bisphenols and one triphenol were synthesized using enzymatic catalysis. Their antioxidant activity at polymer processing and service temperature was investigated in polypropylene (PP) and polybutylene succinate (PBS). The results were compared to the commercial antioxidant Irganox 1010®. The analysis of the Oxygen Induction Time (OIT) of the polymer degradation at high temperatures showed that Irganox 1010® was more efficient to protect PP than the ferulic acid based bis/trisphenols, while, in the case of PBS, the biobased antioxidants, and in particular tris-O-dihydroferuloyl glycerol, were more efficient. FT-IR analysis of neat and formulated PP stored for two years at room temperature showed no degradation using any antioxidant. Aging studies of PBS at room temperature in dry atmosphere showed that all antioxidants had an equal stabilizing effect on the molecular weight averages of the polymer. The analysis of the mechanism of the antioxidant activity of the ferulic acid derivatives showed the possibility of dimerization through biaryl coupling. In conclusion, ferulic acid based antioxidants can be efficient primary antioxidants for the thermo-oxidative stabilization of polymers.
  • 08 SEP 2016

    Chemo-enzymatic synthesis of chiral epoxides ethyl and methyl (S)-3-(oxiran-2-yl)propanoates from renewable levoglucosenone: An access to enantiopure (S)-Dairy Lactone

    Chiral epoxides—such as ethyl and methyl (S)-3-(oxiran-2-yl)propanoates —are valuable precursors in many chemical syntheses. Until recently, these compounds were synthesized from glutamic acid in four steps (deamination, reduction, tosylation and epoxide formation) in low to moderate overall yield (20%–50%). Moreover, this procedure requires some harmful reagents such as sodium nitrite ((eco)toxic) and borane (carcinogen). Herein, starting from levoglucosenone (LGO), a biobased chiral compound obtained through the flash pyrolysis of acidified cellulose, we propose a safer and more sustainable chemo-enzymatic synthetic pathway involving lipase-mediated Baeyer-Villiger oxidation, palladium-catalyzed hydrogenation, tosylation and treatment with sodium ethoxide/methoxide as key steps. This route afforded ethyl and methyl (S)-3-(oxiran-2-yl)propanoates in 57% overall yield, respectively. To demonstrate the potentiality of this new synthetic pathway from LGO, the synthesis of high value-added (S)-dairy lactone was undertaken from these epoxides and provided the target in 37% overall yield from LGO.
  • 28 JUIN 2016

    Structure Property Relationships of Biobased n-Alkyl Bisferulate Epoxy Resins

    In this work, a series of bio-based chemically recyclable epoxy resins were synthesized from n-alkyl bisferulate esters that do not activate human estrogen receptor alpha (ERα). Viscosities of corresponding glycidyl ether n-alkyl bisferulate resins, determined by steady shear rheology, range from 12-9.4 Pa.s. Activation energies of flow range from 83-96 kJ/mol and are similar to the diglycidyl ether bisphenol A (DGEBA). Thermomechanical properties of diglycidyl ether n-alkyl bisferulate resins cured with isophorone diamine were governed by the length of α,ω-diols that link glycidyl ether ferulate units. That is, the glassy phase modulus and alpha transition temperatures range from 3400-2400 MPa (at 25 °C) and 40-53°C (peak of E”), respectively. Furthermore, the onset of thermal degradation (Td5%) varied from 331-300°C. Chemical recycling of cured epoxy resins was performed by static immersion in 10 w/w sodium hydroxide aqueous solutions at 60 °C. Times required for complete conversion of cured resins to water-soluble degradation products was also α,ω-diol length dependent and varied from 5 to 65 h. Thus, diglycidyl ether of n-alkyl bisferulate resins provides a viable biobased alternative to BPA epoxy resins as well as the option of chemical degradability and recovery of fillers in composite applications.
  • 25 MAI 2016

    ADMET polymerization of biobased monomers deriving from syringaresinol

    Renewable α,ω-dienes have been prepared from syringaresinol, a naturally occurring bisphenol deriving from sinapyl alcohol, and further studied as monomers in ADMET polymerizations. Polymerization was optimized according to catalyst loading and reaction conditions (in mass vs. in solvent), and led to polymers with molecular weight up to 14.1 kDa. Thermal analyses of these new polymers showed excellent thermal stabilities (257–360 °C) and tunable Tg (18–70 °C) depending on the structure of the starting α,ω-diene monomer.
  • 19 AVR 2016

    Lipase-catalyzed Baeyer-Villiger Oxidation of cellulose-derived Levoglucosenone into (S)-gamma-hydroxymethyl-alpha,beta-butenolide: Optimization by Response Surface Methodology

    Cellulose-derived levoglucosenone (LGO) has been efficiently converted into pure (S)-gamma-hydroxymethyl-alpha,beta-butenolide (HBO), a chemical platform suited for the synthesis of drugs, flavors and antiviral agents. This process involves two-steps: a lipase-catalyzed Baeyer-Villager oxidation of LGO followed by an acid hydrolysis of the reaction mixture to provide pure HBO. Response surface methodology (RSM), based on central composite face-centered (CCF) design, was employed to evaluate the factors effecting the enzyme-catalyzed reaction: pka of solid buffer (7.2 - 9.6), LGO concentration (0.5 - 1 M) and enzyme loading (55 - 285 PLU.mmol-1).

    Enzyme loading and pka of solid buffer were found to be important factors to the reaction efficiency (as measured by the conversion of LGO) while only the later had significant effects on the enzyme recyclability (as measured by the enzyme residual activity). LGO concentration influences both responses by its interaction with the enzyme loading and pka of solid buffer.

    The optimal conditions which allow to convert at least 80% of LGO in 2 hours at 40 °C and reuse the enzyme for a subsequent cycle were found to be: solid buffer pka = 7.5, [LGO] = 0.50 M and 113 PLU.mmol-1 for the lipase. A good agreement between experimental and predicted values was obtained and the validity of the model confirmed (p-value 0.05).
  • 02 MAR 2016

    Chemo-enzymatic preparation and characterization of renewable oligomers with bisguaiacol moieties: promising sustainable antiradical/antioxidant additives

    The synthesis, structural characterization and properties of new
bio-based oligomers with bisguaiacol-type moieties esterified by diverse aliphatic linkers are described. These oligomers, produced by oxidative oligomerization of renewable dihydro ferulic acid-based bisphenols with commercially available Trametes versicolor laccase, are proposed as promising sustainable antiradical/antioxidant additives for polymers. This environmental friendly biocatalyzed process is performed under very mild conditions in open vessels, aqueous solution at room temperature.

    Modifications of the reaction conditions (use of an organic co-solvent up to 80% v/v and rise of the reaction temperature up to 60 °C) revealed that the polymerization degree of the oligomers may be controlled by adjusting the nature and the ratio of the co-solvent, the reaction time and the reaction temperature. Thermal analyses (TGA and DSC) demonstrated that these phenolic oligomers exhibit high
 thermal stability and that their Td5% and Tg can be easily tailored by playing with both the structure of the bisphenol and the degree of polymerization.

    Similarly, these phenolic oligomers exhibit tunable potent antiradical/antioxidant activity as shown by DPPH analyses. These aliphatic-aromatic oligomers with bisguaiacol-type moieties are thus promising easily accessible, eco-friendly antiradical/antioxidant
additives for the stabilization of polymers in packaging and other applications.
  • 27 JAN 2016

    Reactive extraction of bio-based 3-hydroxypropionic acid assisted by hollow-fiber membrane contactor using TOA and Aliquat 336 in n-decanol

    Reactive liquid–liquid extraction is a promising technique for the direct recovery of carboxylic acids from bioconversion media. This work focused on the optimization of 3-hydroxypropionic acid (3-HP) reactive extraction assisted by hollow-fiber membrane contactor (HFMC), using tri-n-octylamine (TOA) and Aliquat 336 as extractants in n-decanol, and on its practical application for the recovery of 3-HP obtained from glycerol bioconversion by Lactobacillus reuteri.

    The results underlined the influence of the initial pH and 3-HP concentration of the aqueous medium and the impact of extractant phase composition on the extraction performances. The highest distribution coefficient of 3-HP (KD = 13.0) was observed at pH = 3 with 10% v/v TOA mixed with 10% v/v Aliquat 336 in n-decanol. This study showed that the acid concentration and the ratio of amines used between TOA and Aliquat 336 in n-decanol did not have a great impact on the KD during 3-HP reactive extraction, whereas it had an influence on the extraction kinetics. Moreover, 3-HP reactive extraction assisted by HFMC from real bioconversion broth with glycerol as the substrate was shown to be feasible, with the same order of magnitude of extraction kinetics but with a lower KD compared to reactive extraction using model broth.

    3-HP was predominantly extracted from the bioconversion broth, confirming the high selectivity of the extraction process studied and the high potential of this approach applied to the biotechnological production of 3-HP..
  • 26 NOV 2015

    Structure–Activity Relationships and Structural Design Optimization of a Series of p-Hydroxycinnamic Acids-Based Bis- and Trisphenols as Novel Sustainable Antiradical/Antioxidant Additives

    Chemo-enzymatic synthesis and screening of a library of renewable saturated and unsaturated bis- and trisphenols deriving from p-hydroxycinnamic acids (i.e., p-coumaric acid, ferulic acid, and sinapic acid) and biobased diols/triol (i.e., isosorbide, 1,4-... Analysis of bis- and trisphenols deriving from p-hydroxycinnamic acids showed them to be promising, ecofriendly, and sustainable antiradical/antioxidant additives.
  • 05 NOV 2015

    3-Hydroxypropionaldehyde (3-HPA) quantification by HPLC using a synthetic acrolein-free 3-hydroxypropionaldehyde system as analytical standard

    HPLC-based quantification of 3-HPA using a synthetic acrolein-free 3-HPA standard obtained from commercially available 1,2,4-butanetriol through a straightforward and easy synthetic process has advantages over previous colorimetric methods of easier and safer implementation, and greater specificity. This HPLC method is very simple to implement in a lab, does not need any extra handling of the sample to be analyzed, and is suitable even in the presence of other aldehydes and 3-HPA derivatives, provided that the latter do not have similar retention times.
  • 22 OCT 2015

    Diversity of Lactobacillus reuteri Strains in Converting Glycerol into 3-Hydroxypropionic Acid

    The present study aims at comparing the performances of three Lactobacillus reuteri strains (DSM 20016, DSM 17938, and ATCC 53608) in producing 3-hydroxypropionic acid (3-HP) from glycerol and at exploring inhibition phenomena during this bioconversion. Differences were highlighted between the three strains in terms of 3-HP production yield, kinetics of substrate consumption, and metabolite production. With a maximal productivity in non-optimal conditions (free pH) around 2 g.L(-1).h(-1) of 3-HP and 4 g.L(-1).h(-1) of 3-hydroxypropionaldehyde (3-HPA) depending on the strain, this study confirmed the potential of L. reuteri for the biotechnological production of 3-HP. Moreover, the molar ratios of 3-HP to 1,3-propanediol (1,3-PDO) obtained for the three strains (comprised between 1.25 and 1.65) showed systematically a higher 3-HP production. From these results, the DSM 17938 strain appeared to be the most promising strain. The impact of glycerol bioconversion on the bacteria's physiological state (a decrease of around 40 % in DSM 17938 cells showing an enzymatic activity after 3 h) and survival (total loss of cultivability after 2 or 3 h depending on the strains) was revealed and discussed. The effect of each metabolite on L. reuteri DSM 17938 was further investigated, displaying a drastic inhibition caused by 3-HPA, while 3-HP induced lower impact and only at acidic pH.
  • 22 OCT 2015

    Relationships between the use of Embden Meyerhof pathway (EMP) or Phosphoketolase pathway (PKP) and lactate production capabilities of diverse Lactobacillus reuteri strains

    The aims of this study is to compare the growth and glucose metabolism of three Lactobacillus reuteri strains (i.e. DSM 20016, DSM 17938, and ATCC 53608) which are lactic acid bacteria of interest used for diverse applications such as probiotics implying the production of biomass, or for the production of valuable chemicals (3-hydroxypropionaldehyde, 3-hydroxypropionic acid, 1,3-propanediol). However, the physiological diversity inside the species, even for basic metabolisms, like its capacity of acidification or glucose metabolism, has not been studied yet. In the present work, the growth and metabolism of three strains representative of the species diversity have been studied in batch mode. The strains were compared through characterization of growth kinetics and evaluation of acidification kinetics, substrate consumption and product formation. The results showed significant differences between the three strains which may be explained, at least in part, by variations in the distribution of carbon source between two glycolytic pathways during the bacterial growth: the phosphoketolase or heterolactic pathway (PKP) and the Embden-Meyerhof pathway (EMP). It was also shown that, in the context of obtaining a large amount of biomass, DSM 20016 and DSM 17938 strains were the most effective in terms of growth kinetics. The DSM 17938 strain, which shows the more significant metabolic shift from EMP to PKP when the pH decreases, is more effective for lactate production.
  • 22 OCT 2015

    Reactive extraction of 3-hydroxypropionic acid from model aqueous solutions and real bioconversion media. Comparison with its isomer 2-hydroxypropionic (lactic) acid

    Bioconversion is a promising route to produce bio-based building blocks such as 3-hydroxypropionic acid (3-HP). Reactive extraction can be used for 3-HP recovery, and ultimately integrated to the bioconversion process. To the best of our knowledge, there is no published experimental data about the reactive extraction of 3-HP. This work aimed to study the extraction of 3-HP using tri-n-octylamine and Aliquat 336 as extractants in n-decanol. Comparison was also made with its positional isomer, lactic acid. Finally, the extraction of 3-HP from model and real bioconversion broths was examined.
  • 29 NOV 2014

    Renewable polymers derived from ferulic acid and bio-based diols via ADMET

    Renewable α,ω-diene monomers have been prepared from ferulic acid, bio-sourced diols (isosorbide and butanediol) and bromo-alkenes using a chemo-enzymatic synthetic pathway then studied as monomers in ADMET polymerisation. All monomers and polymers have been thoroughly characterised using NMR, GPC, DSC and TGA. ADMET polymerisation was optimised with regard to catalyst loading (Hoveyda–Grubbs II), reaction medium (in mass vs. in solvent), and temperature, which led to polymers with molecular weight up to 25 kDa. Thermal analysis of these new poly(ester-alkenamer)s showed excellent thermal stabilities (283–370 °C) and tunable Tg depending on the nature of the bio-based diol and the chain length of the alkene in the α,ω-diene monomer.
  • 05 SEP 2014

    Chemo-enzymatic synthesis of key intermediates (S)-γ-hydroxymethyl-α,β-butenolide and (S)-γ-hydroxymethyl-γ-butyrolactone via lipase-mediated Baeyer–Villiger oxidation of levoglucosenone

    Levoglucosenone, a valuable chiral platform chemical that can be efficiently produced from catalytic fast pyrolysis of cellulose, has been efficiently converted into optically pure (S)-γ-hydroxymethyl-α,β-butenolide using a two-step sequence involving a lipase-mediated Baeyer–Villiger oxidation and an acid hydrolysis. In the same fashion, (S)-γ-hydroxymethyl-γ-butyrolactone was successfully obtained through a three-step sequence (Baeyer–Villiger, palladium-catalysed hydrogenation and acid hydrolysis). The use of solid buffers in the lipase-mediated Baeyer–Villiger oxidation has been proved beneficial in two ways: not only the reaction time and the enzymatic load were both reduced four-fold (from 8 to 2 hours and 464 to 113 U mmol−1) to reach conversions ≥83%, but solid buffers also prevented lipase from denaturation, thus preserving its enzymatic activity and allowing its use for further oxidation cycles.