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Thauera aminoaromatica MZ1T Identified as a Polyhydroxyalkanoate-Producing Bacterium within a Mixed Microbial Consortium

Polyhydroxyalkanoates (PHAs) form a highly promising class of bioplastics for the transition from fossil fuel-based plastics to bio-renewable and biodegradable plastics. Mixed microbial consortia (MMC) are known to be able to produce PHAs from organic waste streams. Knowledge of key-microbes and their characteristics in PHA-producing consortia is necessary for further process optimization and direction towards synthesis of specific types of PHAs. In this study, a PHA-producing mixed microbial consortium (MMC) from an industrial pilot plant was characterized and further enriched on acetate in a laboratory-scale selector with a working volume of 5 L. 16S-rDNA microbiological population analysis of both the industrial pilot plant and the 5 L selector revealed that the most dominant species within the population is Thauera aminoaromatica MZ1T, a Gram-negative beta-proteobacterium belonging to the order of the Rhodocyclales. The relative abundance of this Thauera species increased from 24 to 40% after two months of enrichment in the selector-system, indicating a competitive advantage, possibly due to the storage of a reserve material such as PHA. First experiments with T. aminoaromatica MZ1T showed multiple intracellular granules when grown in pure culture on a growth medium with a C:N ratio of 10:1 and acetate as a carbon source. Nuclear magnetic resonance (NMR) analyses upon extraction of PHA from the pure culture confirmed polyhydroxybutyrate production by T. aminoaromatica MZ1T.

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Van afval naar grondstof

In het dagelijks leven hebben we voortdurend met verschillende plastics te maken. Overal om ons heen komen we plastics tegen. Denk bijvoorbeeld aan verpakkingsmaterialen, flessen, flacons, kratten, tapijten en plastic draagtassen. Een leven zonder kunststoffen is in onze huidige maatschappij vrijwel ondenkbaar geworden. In 2014 werd er volgens Plastics Europe [1] wereldwijd maar liefst 311.000.000 ton aan kunststoffen geproduceerd, in 1950 was dit nog slechts 1.700.000 ton. Vanaf 1950 stijgt de wereldwijde productie van kunststoffen met gemiddeld 9% per jaar. Bij de huidige productiecapaciteit komt dit volgens Plastics Europe neer op gemiddeld 40 kg/jaar per hoofd van de wereldbevolking! Naar verwachting zal het gebruik van plastics verder toenemen naar gemiddeld 87 kg/jaar per hoofd van de wereldbevolking in het jaar 2050. In Nederland ligt het verbruik momenteel op gemiddeld 126 kg per inwoner. Maar volgens prognoses van VLEEM (Very Long Term Energy Environment Model) [2] zal dit groeien naar gemiddeld 220 kg per inwoner in 2050!! De toenemende vraag naar plastics wordt mede veroorzaakt omdat plastics op zich een gemakkelijk te verwerken materiaal is. Plastics zijn relatief goedkoop, hebben een lage specifieke dichtheid (t.o.v. bijvoorbeeld metalen), en zijn snel en gemakkelijk verwerkbaar.

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People. Planet. Polymer: een Wereld te Winnen [Inaugurele rede]

Positioning paper bij de inauguratie van Vincent Voet als lector Circular Plastics.

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People. Planet. Polymer: een Wereld te Winnen [Inaugurele rede]

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Development Midstream processing of Flax-fiber

Stricter environmental policies, increased energy prices and depletion of resources are forcing industries to look for bio-based and low carbon footprint products. For industries, flax is interesting resource since it is light, strong, environmental friendly and renewable. From flax plant to fiber products involves biochemical and mechanical processes. Moreover, production and processing costs have to compete with other products, like petroleum based materials. This research focusses on sustainable process improvement from flax plant to fiber production. Flax retting is a biological process at which mainly pectin is removed. Without retting, the desired fibre remains attached to the wooden core of the flax stem. As a result, the flax fibres cannot be gained, or have a lows quality. After retting, the fibers are released from the wooden core. Furthermore, machines have been introduced in the flax production process, but the best quality fibers are still produced manually. Due to the high labor intensity the process is too expensive and the process needs to be economical optimized. Since the retting process determines all other downstream processes, retting is the first step to focus on. Lab-scale experiments were performed to investigate the retting process. Factors that were researched were low cost processing conditions like, temperature, pH, dew retting and water retting. The retting rate was low, around three weeks for complete retting. The best retting conditions were at 20°C with water and any addition of chemicals. The process could be shortened to two weeks by recycling the water phase. In a scale-up experiment, a rotating drum was used at the optimal conditions from the lab-experiment (20°C and water). First the flax did not mix with the water content in the rotating drum. The flax was too rigid and did not tumble. Therefore, bundles of flax plants were used. The inner core of the bundle seemed to be protected and the retting rate was less compared to the flax on the surface of the flax bundle. This implies that mechanical impact increased retting in the rotating drum, however heterogeneous retting should be avoided. To overcome the heterogeneous retting problem, a water column was used to improve heterogeneous retting. Retting was performed in a water column and mixing was accomplished by bubbling air. As a result of the mixing, the flax bundle was retted homogenously. And after drying, it was possible to separate the fibers from the wooden flax core. Retting with a bubble column can overcome this problem and seems to be a usable retting process step. Water samples of the lab-scale experiments, the rotating drum and the bubble column showed a chemical oxygen demand (COD) content up to 4 g/L. Overall, 1 kg Flax resulted in 40 g COD. This indicates the possibility to produce biogas that can be used for generating heat and electricity, to make the process sustainable. Around 50% of the weight consists of wooden shives. The shives can be used for pyrolysis and it was possible to produce around 30% coal and 20% oil. These compounds can be used as building blocks, but also to generate heat and electricity. Heat and electricity can be used for the flax processing. Shives were only dried for 1 day at 105°C and slow pyrolysis was used. This indicates that a higher yield can be expected at fast pyrolysis. Overall, the reported implicates that quality fiber production from flax plant can be a feasible, sustainable and a renewable production process. Feasibility of the process can be obtained by, (1) retting at low-cost process conditions of 20°C and using water without any addition of chemicals, (2) with increased flax retting rate by recycling water, (3) with increased flax retting rate by introducing mixing forces, and the ability to lower the energy consumption of the overall process, (4) producing biogas from the COD with anaerobic digestion and (5) producing pyrolysis oil and pyrolysis c

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Conversion of a Xylose-rich Stream from Biomass-biorefining into Polyhydroxyalkanoate (PHA) by Schlegelella thermodepolymerans

The transition to a biobased economy necessitates utilizing renewable resources as a sustainable alternative to traditional fossil fuels. Bioconversion is a way to produce many green chemicals from renewables, e.g., biopolymers like PHAs. However, fermentation and bioconversion processes mostly rely on expensive, and highly refined pure substrates. The utilization of crude fractions from biorefineries, especially herbaceous lignocellulosic feedstocks, could significantly reduce costs. This presentation shows the microbial production of PHA from such a crude stream by a wild-type thermophilic bacterium Schlegelella thermodepolymerans [1]. Specifically, it uses crude xylose-rich fractions derived from a newly developed biorefinery process for grassy biomasses (the ALACEN process). This new stepwise mild flow-through biorefinery approach for grassy lignocellulosic biomass allows the production of various fractions: a fraction containing esterified aromatics, a monomeric xylose-rich stream, a glucose fraction, and a native-like lignin residue [2]. The crude xylose-rich fraction was free of fermentation-inhibiting compounds meaning that the bacterium S.thermodepolymerans could effectively use it for the production of one type of PHA, polyhydroxybutyrate. Almost 90% of the xylose in the refined wheat straw fraction was metabolized with simultaneous production of PHA, matching 90% of the PHA production per gram of sugars, comparable to PHA yields from commercially available xylose. In addition to xylose, S. thermodepolymerans converted oligosaccharides with a xylose backbone (xylans) into fermentable xylose, and subsequently utilized the xylose as a source for PHA production. Since the xylose-rich hydrolysates from the ALACEN process also contain some oligomeric xylose and minor hemicellulose-derived sugars, optimal valorization of the C5-fractions derived from the refinery process can be obtained using S. thermodepolymerans. This opens the way for further exploration of PHA production from C5-fractions out of a variety of herbaceous lignocellulosic biomasses using the ALACEN process combined with S. thermodepolymerans. Overall, the innovative utilization of renewable resources in fermentation technology, as shown herein, makes a solid contribution to the transition to a biobased economy.[1] W. Zhou, D.I. Colpa, H. Permentier, R.A. Offringa, L. Rohrbach, G.J.W. Euverink, J. Krooneman. Insight into polyhydroxyalkanoate (PHA) production from xylose and extracellular PHA degradation by a thermophilic Schlegelella thermodepolymerans. Resources, Conservation and Recycling 194 (2023) 107006, ISSN 0921-3449, https://doi.org/10.1016/j.resconrec.2023.107006. [2] S. Bertran-Llorens, W.Zhou. M.A.Palazzo, D.I.Colpa, G.J.W.Euverink, J.Krooneman, P.J.Deuss. ALACEN: a holistic herbaceous biomass fractionation process attaining a xylose-rich stream for direct microbial conversion to bioplastics. Submitted 2023.

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Products 109

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Thauera aminoaromatica MZ1T Identified as a Polyhydroxyalkanoate-Producing Bacterium within a Mixed Microbial Consortium

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Van afval naar grondstof

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People. Planet. Polymer: een Wereld te Winnen [Inaugurele rede]

Positioning paper bij de inauguratie van Vincent Voet als lector Circular Plastics.

PDF

product

Development Midstream processing of Flax-fiber

MULTIFILE

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Conversion of a Xylose-rich Stream from Biomass-biorefining into Polyhydroxyalkanoate (PHA) by Schlegelella thermodepolymerans

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Products 109

Thauera aminoaromatica MZ1T Identified as a Polyhydroxyalkanoate-Producing Bacterium within a Mixed Microbial Consortium

Van afval naar grondstof

People. Planet. Polymer: een Wereld te Winnen [Inaugurele rede]

3D Printing with biomaterials

The interaction between business modelling and networking across the life cycle of eco-sustainable innovations

Development Midstream processing of Flax-fiber

From wilderness to plastic flowers and mowed lawns

Biomethane from hydrogen and carbon dioxide

Conversion of a Xylose-rich Stream from Biomass-biorefining into Polyhydroxyalkanoate (PHA) by Schlegelella thermodepolymerans

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Products 109

Thauera aminoaromatica MZ1T Identified as a Polyhydroxyalkanoate-Producing Bacterium within a Mixed Microbial Consortium

Van afval naar grondstof

People. Planet. Polymer: een Wereld te Winnen [Inaugurele rede]

3D Printing with biomaterials

The interaction between business modelling and networking across the life cycle of eco-sustainable innovations

Development Midstream processing of Flax-fiber

From wilderness to plastic flowers and mowed lawns

Biomethane from hydrogen and carbon dioxide

Conversion of a Xylose-rich Stream from Biomass-biorefining into Polyhydroxyalkanoate (PHA) by Schlegelella thermodepolymerans