Filippo Fabbri

The potential of three thermophilic enzymes from the α,β-hydrolases superfamily, that have recently been described for polyester hydrolysis, was investigated for polyester synthesis, esterification and transesterification reactions. The hydrolases (LCC, leaf-branch compost cutinase; its variant LCCICCG, Thb from Thermoanaerobacterales bacterium) were recombinantly expressed, purified and immobilized onto polypropylene beads. A design of experiments (DoE) assisted study was performed to investigate their synthetic potential to produce short flavor esters by analyzing their thermostability and selectivity towards alcohols and acids with different chain lengths. The factors considered in the DoE (i.e., temperature, alcohol chain length, acid chain length and reaction time) were optimized using MODDE® software to generate a predictive model defining the optimal synthetic conditions for the three enzymes. In each experiment, the monitored response was the acid conversion rate, quantified with GC-FID analysis. For synthesis, the temperature optima of LCC, LCCICCG and Thb were 60 °C, 55 °C, and 80 °C, respectively, corresponding to the maximum percentage of monomers conversion for long-chain alcohols and acids as substrates. Polymerization of dimethyl adipate and 1,8-octanediol as building blocks was carried out to confirm the applicability of the obtained model for the synthesis of larger macromolecules via polycondensation reactions. Conversion of monomers, as determined by nuclear magnetic resonance (NMR) analysis, was ~90% for all enzymes while the average molecular weights (Mn) of the polyesters, analyzed by gel permeation chromatography, were between 3600 Da, for LCC and its variant LCCICCG, and 3800 Da for Thb.

The increasing drug consumption worldwide raises environmental and health concerns, as pharmaceutical residues entering the environment pose risks to both ecosystems and human health. Enzyme remediation has been emerging in recent decades as a possible solution to eliminate recalcitrant pharmaceutical pollutants in wastewater or contaminated sites, offering a faster alternative to microbial remediation, e.g., without the need for microbial growth or adaptation. Moreover, enzymes operate under a wider range of conditions, avoiding biomass formation and disposal, and antibiotic resistance risks. In the present study, high amounts (up to 5000 mg/L) of trazodone hydrochloride and its by-products, namely Impurity H and Compound F, were enzymatically treated using a laccase-mediator system consisting of the laccase from Trametes hirsuta (ThL) and the mediator 1-hydroxybenzotriazole (HBT). Different concentrations of an organic solvent system composed of acetone and isobutyl alcohol in a 1:1 ratio and up to 20% (v/v) were employed to simulate the matrix of a real industrial production waste stream. Thereby, the enzymatic oxidation of trazodone hydrochloride and its by-products was not significantly affected by the varying solvent concentrations, resulting in maximum conversions of 62%, 73% and 62% of trazodone hydrochloride, impurity H, and impurity F, respectively. Liquid chromatography—high-resolution mass spectrometry (LC-HRMS) indicated preferential oxidation of the piperazine group in all three molecules. In vivo ecotoxicity experiments must be carried out in the future to assess the toxicological and environmental behaviour of the obtained degradation products. This work emphasised the potential role of enzymes in supporting the transition towards a more sustainable pharmaceutical industry.

Polylactic acid (PLA) is a widely used biopolymer, but its brittleness and limited biodegradability hinder its application as a standalone material. To enhance its properties, PLA can be compounded with plasticizers, ideally nontoxic and from sustainable sources. While phthalates remain the predominant plasticizers, their known harmful effects have led to the development of bio‐based alternatives like glycerol trilevulinate (GT). This study investigates the plasticizing effect of GT on amorphous (aPLA) and semi‐crystalline (cPLA) PLA, comparing it to the impact that can be achieved with a conventional plasticizer, diisononyl cyclohexane‐1,2‐dicarboxylate (DINCH). Specifically, GT added at 40 phr reduces the glass transition temperature of aPLA by 20°C and the melting temperature of cPLA by 12°C, whereas DINCH exhibited a more limited effect. Compared to DINCH, GT also demonstrated very low migration in terms of both leaching and volatility. Moreover, GT impacts on the enzymatic depolymerization of the prepared compounds. Specifically, enzymatic hydrolysis tests revealed an enhanced biodegradability of the aPLA/GT compounds, achieving complete degradation within 72 h of incubation, as confirmed by high performance liquid chromatography‐based monomer quantification. The cPLA/GT formulations are also susceptible to hydrolysis, showing an increased weight loss from 18% to 31% when 20 phr of GT is added. These outcomes suggest that GT can be used not only to tune the thermal properties but also to significantly promote polyesters biodegradability, envisioning an environmentally friendly management of the PLA‐based formulations. Highlights: A bioplasticizer for amorphous and semi‐crystalline PLA is proposed. Bioplasticizer reduces the glass transition and melting temperature of PLAs. Bioplasticizer also enhances the enzymatic degradation of semi‐crystalline PLA. Bioplasticizer performance has been compared with a commercial plasticizer.

The present study proposes enzymatic polymerization reactions to synthesize polyesters employing lipase (CaLB) covalently immobilized onto magnetic nanoparticles (i.e., Biocatalyst Magnetic Nanoarchitecture).

In the present work, Mycobacterium smegmatis acyltransferase (MsAcT) was successfully immobilized onto polypropylene beads and the selectivity was investigated both in esterification and polycondensation reactions.

A reliance on fossil fuel has led to the increased emission of greenhouse gases (GHGs). The excessive consumption of raw materials today makes the search for sustainable resources more pressing than ever. Technical lignins are mainly used in low-value applications such as heat and electricity generation. Green enzyme-based modifications of technical lignin have generated a number of functional lignin-based polymers, fillers, coatings, and many other applications and materials. These bio-modified technical lignins often display similar properties in terms of their durability and elasticity as fossil-based materials while also being biodegradable. Therefore, it is possible to replace a wide range of environmentally damaging materials with lignin-based ones. By researching publications from the last 20 years focusing on the latest findings utilizing databases, a comprehensive collection on this topic was crafted. This review summarizes the recent progress made in enzymatically modifying technical lignins utilizing laccases, peroxidases, and lipases. The underlying enzymatic reaction mechanisms and processes are being elucidated and the application possibilities discussed. In addition, the environmental assessment of novel technical lignin-based products as well as the developments, opportunities, and challenges are highlighted.

In the present work, different hydrolases were adsorbed onto polypropylene beads to investigate their activity both in short-esters and polyesters synthesis. The software MODDE^® Pro 13 (Sartorius) was used to develop a full-factorial design of experiments (DoE) to analyse the thermostability and selectivity of the immobilized enzyme towards alcohols and acids with different chain lengths in short-esters synthesis reactions. The temperature optima of Candida antarctica lipase B (CaLB), Humicola insolens cutinase (HiC), and Thermobifida cellulosilytica cutinase 1 (Thc_Cut1) were 85 °C, 70 °C, and 50 °C. CaLB and HiC preferred long-chain alcohols and acids as substrate in contrast to Thc_Cut1, which was more active on short-chain monomers. Polymerization of different esters as building blocks was carried out to confirm the applicability of the obtained model on larger macromolecules. The selectivity of both CaLB and HiC was investigated and best results were obtained for dimethyl sebacate (DMSe), leading to polyesters with a M_w of 18 kDa and 6 kDa. For the polymerization of dimethyl adipate (DMA) with BDO and ODO, higher molecular masses were obtained when using CaLB onto polypropylene beads (CaLB_PP) as compared with CaLB immobilized on macroporous acrylic resin beads (i.e., Novozym 435). Namely, for BDO the M_n were 7500 and 4300 Da and for ODO 8100 and 5000 Da for CaLB_PP and for the commercial enzymes, respectively. Thc_Cut1 led to polymers with lower molecular masses, with M_n < 1 kDa. This enzyme showed a temperature optimum of 50 °C with 63% of DMA and BDO when compared to 54% and 27%, at 70 °C and at 85 °C, respectively.