Keratinous and corneous-based products towards circular bioeconomy: A research review.

Keratins and corneous proteins are key components of biomaterials used in a wide range of applications and are potential substitutes for petrochemical-based products. Horns, hooves, feathers, claws, and similar animal tissues are abundant sources of α-keratin and corneous β-proteins, which are by-products of the food industry. Their close association with the meat industry raises environmental and ethical concerns regarding their disposal.

Systematic screening for the biocatalytic hydration of fatty acids from different oily substrates by Elizabethkingia meningoseptica oleate hydratase through a Design-of-experiments approach.

The edible plant oils production is associated with the release of different types of by-products. The latter represent cheap and available substrates to produce valuable compounds, such as flavours and fragrances, biologically active compounds and bio-based polymers. Elizabethkingia meningoseptica Oleate hydratases (Em_OhyA) can selectively catalyze the conversion of unsaturated fatty acids, specifically oleic acid, into hydroxy fatty acids, which find different industrial applications.

Industrial Production of Proteins with -.

Since the mid-1960s, methylotrophic yeast (previously described as ) has received increasing scientific attention. The interest for the industrial production of proteins for different applications (e.g.

A comparative screening of laccase-mediator systems by white-rot fungi laccases for biocatalytic benzyl alcohol oxidation.

Production of value-added compounds from waste materials is of utmost importance for the development of a sustainable society especially regarding their use as catalysts in industrially relevant synthetic reactions. Herein, we show the production of laccases from four white-rot fungi, which were grown on agricultural residues, specifically Trametes versicolor 11269, Pleurotus ostreatus 1020, Panus tigrinus 707 and Lentinula edodes SC-495. The produced laccases were tested on a laccase-mediator system (LMS) for the biocatalytic oxidation of the model substrate benzyl alcohol into benzaldehyde.

Regio- and stereoselective biocatalytic hydration of fatty acids from waste cooking oils en route to hydroxy fatty acids and bio-based polyesters.

The development of biorefinery approaches is of great relevance for the sustainable production of valuable compounds. In accordance with circular economy principles, waste cooking oils (WCOs) are renewable resources and biorefinery feedstocks, which contribute to a reduced impact on the environment. Frequently, this waste is wrongly disposed of into municipal sewage systems, thereby creating problems for the environment and increasing treatment costs in wastewater treatment plants.

Pinene-Based Oxidative Synthetic Toolbox for Scalable Polyester Synthesis.

Generation of renewable polymers is a long-standing goal toward reaching a more sustainable society, but building blocks in biomass can be incompatible with desired polymerization type, hampering the full implementation potential of biomaterials. Herein, we show how conceptually simple oxidative transformations can be used to unlock the inherent reactivity of terpene synthons in generating polyesters by two different mechanisms starting from the same α-pinene substrate. In the first pathway, α-pinene was oxidized into the bicyclic verbanone-based lactone and subsequently polymerized into star-shaped polymers via ring-opening polymerization, resulting in a biobased semicrystalline polyester with tunable glass transition and melting temperatures.

Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular Textiles.

Although recovery of fibers from used textiles with retained material quality is desired, separation of individual components from polymer blends used in today's complex textile materials is currently not available at viable scale. Biotechnology could provide a solution to this pressing problem by enabling selective depolymerization of recyclable fibers of natural and synthetic origin, to isolate constituents or even recover monomers. We compiled experimental data for biocatalytic polymer degradation with a focus on synthetic polymers with hydrolysable links and calculated conversion rates to explore this path The analysis emphasizes that we urgently need major research efforts: beyond cellulose-based fibers, biotechnological-assisted depolymerization of plastics so far only works for polyethylene terephthalate, with degradation of a few other relevant synthetic polymer chains being reported.

Engineering of Ancestors as a Tool to Elucidate Structure, Mechanism, and Specificity of Extant Terpene Cyclase.

Structural information is crucial for understanding catalytic mechanisms and to guide enzyme engineering efforts of biocatalysts, such as terpene cyclases. However, low sequence similarity can impede homology modeling, and inherent protein instability presents challenges for structural studies. We hypothesized that X-ray crystallography of engineered thermostable ancestral enzymes can enable access to reliable homology models of extant biocatalysts.

Switched reaction specificity in polyesterases towards amide bond hydrolysis by enzyme engineering.

The recalcitrance of plastics like nylon and other polyamides contributes to environmental problems ( microplastics in oceans) and restricts possibilities for recycling. The fact that hitherto discovered amidases (EC 3.5.

A Retro-biosynthesis-Based Route to Generate Pinene-Derived Polyesters.

Significantly increased production of biobased polymers is a prerequisite to replace petroleum-based materials towards reaching a circular bioeconomy. However, many renewable building blocks from wood and other plant material are not directly amenable for polymerization, due to their inert backbones and/or lack of functional group compatibility with the desired polymerization type. Based on a retro-biosynthetic analysis of polyesters, a chemoenzymatic route from (-)-α-pinene towards a verbanone-based lactone, which is further used in ring-opening polymerization, is presented.

Biocatalysis for terpene-based polymers.

Accelerated generation of bio-based materials is vital to replace current synthetic polymers obtained from petroleum with more sustainable options. However, many building blocks available from renewable resources mainly contain unreactive carbon-carbon bonds, which obstructs their efficient polymerization. Herein, we highlight the potential of applying biocatalysis to afford tailored functionalization of the inert carbocyclic core of multicyclic terpenes toward advanced materials.

Towards Sustainable High-Performance Thermoplastics: Synthesis, Characterization, and Enzymatic Hydrolysis of Bisguaiacol-Based Polyesters.

The utilization of wood-derived building blocks (xylochemicals) to replace fossil-based precursors is an attractive research subject of modern polymer science. Here, we demonstrate that bisguaiacol (BG), a lignin-derived bisphenol analogue, can be used to prepare biobased polyesters with remarkable thermal properties. BG was treated with different activated diacids to investigate the effect of co-monomer structures on the physical properties of the products.

Surface engineering of polyester-degrading enzymes to improve efficiency and tune specificity.

Certain members of the carboxylesterase superfamily can act at the interface between water and water-insoluble substrates. However, nonnatural bulky polyesters usually are not efficiently hydrolyzed. In the recent years, the potential of enzyme engineering to improve hydrolysis of synthetic polyesters has been demonstrated.

Synergistic effect of mutagenesis and truncation to improve a polyesterase from Clostridium botulinum for polyester hydrolysis.

The activity of the esterase (Cbotu_EstA) from Clostridium botulinum on the polyester poly(ethylene terephthalate) (PET) was improved by concomitant engineering of two different domains. On the one hand, the zinc-binding domain present in Cbotu_EstA was subjected to site-directed mutagenesis. On the other hand, a specific domain consisting of 71 amino acids at the N-terminus of the enzyme was deleted.

Enzymes as Enhancers for the Biodegradation of Synthetic Polymers in Wastewater.

Synthetic polyesters are today the second-largest class of ingredients in household products and are entering wastewater treatment plants (WWTPs) after product utilization. One approach to improve polymer biodegradation in wastewater would be to complement current processes with polyester-hydrolyzing enzymes and their microbial producers. In this study, the hydrolysis of poly(oxyethylene terephthalate) polymer by hydrolases from wastewater microorganisms was investigated in vitro and under realistic WWTP conditions.

Polyester hydrolysis is enhanced by a truncated esterase: Less is more.

An esterase from Clostridium botulinum (Cbotu_EstA) previously reported to hydrolyze the biodegradable polyester poly(butylene adipate-co-terephthalate) was redesigned to improve the hydrolysis of synthetic polyesters. Increased activity was indeed observed for del71Cbotu_EstA variant, which performed activity on the widespread polyester polyethylene terephthalate, which was not able to be attacked by the wild-type enzyme Cbotu_EstA. Analysis of the 3D structure of the enzyme showed that removing 71 residues at the N-terminus of the enzyme exposed a hydrophobic patch on the surface and improved sorption of hydrophobic polyesters concomitantly facilitating the access of the polymer to the active site.

Characterization of a poly(butylene adipate-co-terephthalate)- hydrolyzing lipase from Pelosinus fermentans.

Certain α/β hydrolases have the ability to hydrolyze synthetic polyesters. While their partial hydrolysis has a potential for surface functionalization, complete hydrolysis allows recycling of valuable building blocks. Although knowledge about biodegradation of these materials is important regarding their fate in the environment, it is currently limited to aerobic organisms.