Phosphate limitation alleviates the inhibitory effect of manganese on itaconic acid production by Aspergillus terreus

UV-Curing Additive Manufacturing of Bio-Based Thermosets: Effect of Diluent Concentration on Printing and Material Properties of Itaconic Acid-Based Materials

In the quest toward sustainable thermosets, research has been conducted on various polymer classes like epoxy, benzoxazines, acryl-/methacrylates, etc. One particular group that can also be utilized as sustainable inks for additive manufacturing is itaconic acid-based unsaturated polyester resins. However, due to increased viscosity of the resins, the use of reactive diluents is required to increase their processability. While research has focused on creating different polymeric structures to expand the possible applications, the required amount of diluent has not received equal attention. In this work, a group of itaconic acid-based polyesters was synthesized to create a series of formulations with different reactive diluent contents. The physicochemical properties of the prepared formulations, along with their reactivity toward UV light, were assessed via photo-differential scanning calorimetry (photo-DSC), real-time attenuated total reflectance (RT-ATR), and photorheology measurements. The same formulations were then used to fabricate test specimens via digital light processing (DLP) three-dimensional (3D) printing, which were examined as to their thermomechanical properties by means of dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) measurements.

Microbial itaconic acid bioproduction towards sustainable development: Insights, challenges, and prospects

Microbial biomanufacturing is a promising approach to produce high-value compounds with low-carbon footprint and significant economic benefits. Among twelve "Top Value-Added Chemicals from Biomass", itaconic acid (IA) stands out as a versatile platform chemical with numerous applications. IA is naturally produced by Aspergillus and Ustilago species through a cascade enzymatic reaction between aconitase (EC 4.2.1.3) and cis-aconitic acid decarboxylase (EC 4.1.1.6). Recently, non-native hosts such as Escherichia coli, Corynebacterium glutamicum, Saccharomyces cerevisiae, and Yarrowia lipolytica have been genetically engineered to produce IA through the introduction of key enzymes. This review provides an up-to-date summary of the progress made in IA bioproduction, from native to engineered hosts, covers in vivo and in vitro approaches, and highlights the prospects of combination tactics. Current challenges and recent endeavors are also addressed to envision comprehensive strategies for renewable IA production in the future towards sustainable development goals (SDGs).

Sustainable Downstream Separation of Itaconic Acid Using Carbon-Based Adsorbents

Separation of itaconic acid from aqueous solution has been explored using various carbon-based adsorbents obtained from the pyrolysis and KOH activation of coconut shell biomass. The best preparation conditions to obtain a tailored adsorbent for itaconic acid purification were identified via a Taguchi experimental design, where its adsorption properties were maximized. The best activated carbon was obtained via coconut shell pyrolysis at 750 °C for 4 h plus an activation with 0.1 KOH and a final treatment at 800 °C for 2 h. This adsorbent showed an adsorption capacity of 4.31 mmol/g at 20 °C and pH 3 with a surface area of 466 m2/g. Itaconic acid separation was exothermic and pH-dependent where electrostatic forces and hydrogen bonding were the main adsorption interactions. Calculated adsorption rate constants for itaconic acid adsorption were 0.44–1.20 h-1. Results of adsorbent characterization analysis indicated the presence of a crystallization of itaconic acid molecules onto the activated carbon surface where 3–4 molecules could interact to form the clusters. This organic acid was recovered from the adsorbent surface via desorption with water or ethanol, thus facilitating its final purification. The best activated carbon obtained in this study is a promising alternative to perform sustainable and energy-efficient downstream separation and purification of itaconic acid produced via fermentation.

Carbon-Source Dependent Interplay of Copper and Manganese Ions Modulates the Morphology and Itaconic Acid Production in Aspergillus terreus

The effects of the interplay of copper(II) and manganese(II) ions on growth, morphology and itaconic acid formation was investigated in a high-producing strain of Aspergillus terreus (NRRL1960), using carbon sources metabolized either mainly via glycolysis (D-glucose, D-fructose) or primarily via the pentose phosphate shunt (D-xylose, L-arabinose). Limiting Mn²⁺ concentration in the culture broth is indispensable to obtain high itaconic acid yields, while in the presence of higher Mn²⁺ concentrations yield decreases and biomass formation is favored. However, this low yield in the presence of high Mn²⁺ ion concentrations can be mitigated by increasing the Cu²⁺ concentration in the medium when D-glucose or D-fructose is the growth substrate, whereas this effect was at best modest during growth on D-xylose or L-arabinose. A. terreus displays a high tolerance to Cu²⁺ which decreased when Mn²⁺ availability became increasingly limiting. Under such conditions biomass formation on D-glucose or D-fructose could be sustained at concentrations up to 250 mg L^–1 Cu²⁺, while on D-xylose- or L-arabinose biomass formation was completely inhibited at 100 mg L^–1. High (>75%) specific molar itaconic acid yields always coincided with an “overflow-associated” morphology, characterized by small compact pellets (<250 μm diameter) and short chains of “yeast-like” cells that exhibit increased diameters relative to the elongated cells in growing filamentous hyphae. At low concentrations (≤1 mg L^–1) of Cu²⁺ ions, manganese deficiency did not prevent filamentous growth. Mycelial- and cellular morphology progressively transformed into the typical overflow-associated one when external Cu²⁺ concentrations increased, irrespective of the available Mn²⁺. Our results indicate that copper ions are relevant for overflow metabolism and should be considered when optimizing itaconic acid fermentation in A. terreus.

Straightforward Synthetic Protocol to Bio-BasedUnsaturated Poly(ester amide)s from Itaconic Acidwith Thixotropic Behavior

In the field of polymer chemistry, tremendous efforts have been made over the last decade to replace petrochemical monomers with building blocks from renewable resources. In this respect, itaconic acid has been used as an alternative to acrylic acid or maleic acid in unsaturated polyesters for thermal or UV-curing applications. However, examples of poly(ester amide)s from itaconic acid are scarce. Under standard polycondensation reactions, the presence of free amines leads to aza-Michael addition reactions at the α,β-unsaturated double bond of the itaconic acid and isomerization reactions to mesaconic acid. Both reactions make the resulting materials useless as UV-curing polymer resins. To avoid these undesired side reactions, we herein report the use of preformed, well-defined diols containing internal amide bonds. The resulting unsaturated poly(ester amide) resins were analyzed before and after UV-induced crosslinking. Viscosity measurements revealed a strong thixotropic behavior induced by the amide groups, which is usually not detected in structurally similar polyester resins.

First Example of Unsaturated Poly(Ester Amide)s Derived From Itaconic Acid and Their Application as Bio-Based UV-Curing Polymers

Recently, itaconic acid has drawn considerable attention as a novel radical-curing building block for polyester resins. These bio-based materials have been used in thermal, as well as ultra violet (UV) curing applications, such as printing inks or coatings. Poly(ester amide)s from itaconic acid could be very interesting, as the amide group could alter the properties of the resins as well as cured materials. However, standard polycondensation reactions with diamines are not possible with itaconic acid as the amines preferably react via an aza-Michael addition at the α,β-unsaturated double bond. Therefore, alternative and more elaborate synthetic strategies have to be developed. Herein, we present two different synthetic strategies to poly(ester amide)s from itaconic acid that circumvent the addition reaction of the amines. This is in both cases done by a pre-reaction to form stable amide building blocks that are then reacted with itaconic acid or polyesters derived thereof. The structural composition and the properties of the resin are characterized, and the UV-curing reactivity is examined. All properties are compared to corresponding polyesters from itaconic acid.

Efficient itaconic acid production by Aspergillus terreus: Overcoming the strong inhibitory effect of manganese

Itaconic acid (IA), a building block platform chemical, is produced industrially by Aspergillus terreus utilizing glucose. Lignocellulosic biomass can serve as a low cost source of sugars for IA production. However, the fungus could not produce IA from dilute acid pretreated and enzymatically saccharified wheat straw hydrolyzate even at 100-fold dilution. Furfural, hydroxymethyl furfural and acetic acid were inhibitory, as is typical, but Mn²⁺ was particularly problematic for IA production. It was present in the hydrolyzate at a level that was 230 times over the inhibitory limit (50 ppb). Recently, it was found that PO₄ ^3- limitation decreased the inhibitory effect of Mn²⁺ on IA production. In the present study, a novel medium was developed for production of IA by varying PO₄ ^3- , Fe³⁺ and Cu²⁺ concentrations using response surface methodology, which alleviated the strong inhibitory effect of Mn²⁺ . The new medium contained 0.08 g KH₂ PO₄ , 3 g NH₄ NO₃ , 1 g MgSO₄ ·7H₂ O, 5 g CaCl₂ ·2 H₂ O, 0.83 mg FeCl₃ ·6H₂ O, 8 mg ZnSO₄ ·7H₂ O, and 45 mg CuSO₄ ·5H₂ O per liter. The fungus was able to produce IA very well in the presence of Mn²⁺ up to 100 ppm in the medium. This medium will be extremely useful for IA production in the presence of Mn²⁺ . This is the first report on the development of Mn²⁺ tolerant medium for IA production by A. terreus.

Manganese Deficiency Is Required for High Itaconic Acid Production From D-Xylose in Aspergillus terreus

Itaconic acid is used as a bio-based, renewable building block in the polymer industry. It is produced by submerged fermentations of the filamentous fungus Aspergillus terreus from molasses or starch, but research over the efficient utilization of non-food, lignocellulosic plant biomass is soaring. The objective of this study was to test whether the application of two key cultivation parameters for obtaining itaconic acid from D-glucose in high yields - Mn2+ ion deficiency and high concentration of the carbon source - would also occur on D-xylose, the principal monomer of lignocellulose. To this end, a carbon and energy balance for itaconic acid formation was established, which is 0.83 moles/mole D-xylose. The effect of Mn2+ ions on itaconic acid formation was indeed similar to that on D-glucose and maximal yields were obtained below 3 μg L-1 Mn2+ ions, which were, however, only 0.63 moles of itaconic acid per mole D-xylose. In contrast to the case on D-glucose, increasing D-xylose concentration over 50 g L-1 did not change the above yield. By-products such as xylitol and α-ketoglutarate were found, but in total they remained below 2% of the concentration of D-xylose. Mass balance of the fermentation with 110 g L-1 D-xylose revealed that >95% of the carbon from D-xylose was accounted as biomass, itaconic acid, and the carbon dioxide released in the last step of itaconic acid biosynthesis. Our data show that the efficiency of biomass formation is the critical parameter for itaconic acid yield from D-xylose under otherwise optimal conditions.